Author: mark
Date: 2004-05-15 01:44:17 -0400 (Sat, 15 May 2004)
New Revision: 490
Added:
trunk/docs/tutorial/tutorial6.htm
trunk/pr/tutorial/tut8.pr
trunk/pr/tutorial/tut9.pr
Modified:
trunk/docs/tutorial/index.htm
trunk/docs/tutorial/tutorial3.htm
trunk/docs/tutorial/tutorial5.htm
Log:
added attributes, vars, and functions to tutorial
Modified: trunk/docs/tutorial/index.htm
===================================================================
--- trunk/docs/tutorial/index.htm 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/docs/tutorial/index.htm 2004-05-15 05:44:17 UTC (rev 490)
@@ -118,7 +118,7 @@
<li><a href="tutorial4.htm#keyrules">Rules about Keys</a>
<li><a href="tutorial4.htm#dictenter">Entering a
Dictionary</a>
<li><a href="tutorial4.htm#dictmutable">Assignment and
del</a>
- <li><a href="tutorial4.htm#mutlist">Dictionary Functions and
+ <li><a href="tutorial4.htm#dictfunc">Dictionary Functions
and
!</a>
</ul>
</ul>
@@ -147,10 +147,46 @@
<li><a href="tutorial5.htm#break">Break Statement</a>
<li><a href="tutorial5.htm#continue">Continue Statement</a>
<li><a href="tutorial5.htm#tags">Loop Block Tags</a>
- <li><a href="tutorial5.htm#else">Else Clause</a>
+ <li><a href="tutorial5.htm#else">Else Clause</a>
<li><a href="tutorial5.htm#bcaesmpl">Sample Code</a>
</ul>
</ul>
+ <li>5. <a href="tutorial6.htm#oav">Attributes, Variables, &
Functions
+ </a>
+ <ul>
+ <li><a href="tutorial6.htm#attr">5.1 Attributes</a>
+ <ul>
+ <li><a href="tutorial6.htm#attrkey">Attribute Keys</a>
+ <li><a href="tutorial6.htm#symbol">Symbols</a>
+ <li><a href="tutorial6.htm#period">Period Operator</a>
+ <li><a href="tutorial6.htm#attrass">Attribute Assignment
&
+ Del </a>
+ </ul>
+ <li><a href="tutorial6.htm#vsw">5.2 Variables, Scope, & With
+ </a>
+ <ul>
+ <li><a href="tutorial6.htm#main">Main Module</a>
+ <li><a href="tutorial6.htm#attr">Variable Scope</a>
+ <li><a href="tutorial6.htm#with">With Statement</a>
+ </ul>
+ <li><a href="tutorial6.htm#funcdef">5.3 Functions & Def
Statement</a>
+ <ul>
+ <li><a href="tutorial6.htm#func">Functions</a>
+ <li><a href="tutorial6.htm#def">Def Statement</a>
+ <li><a href="tutorial6.htm#funcform">Function Calls</a>
+ <li><a href="tutorial6.htm#pos">Positional Params</a>
+ <li><a href="tutorial6.htm#defval">Default Values</a>
+ <li><a href="tutorial6.htm#namematch">Keyword Params</a>
+ <li><a href="tutorial6.htm#starvar">Variable Parameters</a>
+ <li><a href="tutorial6.htm#actstarvar">Variable
Arguments</a>
+ <li><a href="tutorial6.htm#sampleparms">Sample Parameter
Passing</a>
+ <li><a href="tutorial6.htm#localscope">Local Scope</a>
+ <li><a href="tutorial6.htm#passref">Pass By Reference</a>
+ <li><a href="tutorial6.htm#noneobj">None Object</a>
+ <li><a href="tutorial6.htm#rtrnstmt">Return Statement</a>
+ </ul>
+
+ </ul>
</ul>
</td>
</tr>
Modified: trunk/docs/tutorial/tutorial3.htm
===================================================================
--- trunk/docs/tutorial/tutorial3.htm 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/docs/tutorial/tutorial3.htm 2004-05-15 05:44:17 UTC (rev 490)
@@ -21,7 +21,7 @@
<tr>
<td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
Home</a></td>
- <td width="194" valign="middle" align="center" height="25"><a
href="tutorial1.htm">Previous
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial2.htm">Previous
Page</a></td>
<td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
Outline</a></td>
@@ -227,7 +227,7 @@
<tr>
<td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
Home</a></td>
- <td width="194" valign="middle" align="center" height="25"><a
href="tutorial1.htm">Previous
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial2.htm">Previous
Page</a></td>
<td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
Outline</a></td>
Modified: trunk/docs/tutorial/tutorial5.htm
===================================================================
--- trunk/docs/tutorial/tutorial5.htm 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/docs/tutorial/tutorial5.htm 2004-05-15 05:44:17 UTC (rev 490)
@@ -21,11 +21,11 @@
<tr>
<td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
Home</a></td>
- <td width="194" valign="middle" align="center" height="25"><a
href="tutorial3.htm">Previous
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial4.htm">Previous
Page</a></td>
<td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
Outline</a></td>
- <td width="139" valign="middle" align="center" height="25"><a
href="index.htm">Next
+ <td width="139" valign="middle" align="center" height="25"><a
href="tutorial6.htm">Next
Page</a></td>
</tr>
</table>
@@ -276,11 +276,11 @@
<tr>
<td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
Home</a></td>
- <td width="194" valign="middle" align="center" height="25"><a
href="tutorial3.htm">Previous
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial4.htm">Previous
Page</a></td>
<td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
Outline</a></td>
- <td width="139" valign="middle" align="center" height="25"><a
href="index.htm">Next
+ <td width="139" valign="middle" align="center" height="25"><a
href="tutorial6.htm">Next
Page</a></td>
</tr>
</table>
Added: trunk/docs/tutorial/tutorial6.htm
===================================================================
--- trunk/docs/tutorial/tutorial6.htm 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/docs/tutorial/tutorial6.htm 2004-05-15 05:44:17 UTC (rev 490)
@@ -0,0 +1,275 @@
+<html>
+<head>
+<title>Prothon Tutorial - 5.0</title>
+<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
+</head>
+
+<body bgcolor="#FFFFFF" text="#000000">
+<div align="center">
+ <table width="630" border="0" cellpadding="0" cellspacing="0"
bgcolor="#FFFFCC">
+ <tr>
+ <td height="121" width="109"><img src="../images/logo_left.jpg"
width="109" height="135"></td>
+ <td valign="center" height="43">
+ <div align="center"><font size="5" face="Verdana, Arial, Helvetica,
sans-serif">Prothon
+ Tutorial</font></div>
+ </td>
+ <td valign="center" height="121" width="106"><img
src="../images/logo_right.jpg" width="109" height="135"></td>
+ </tr>
+ </table>
+ <br>
+ <table width="630" border="0" cellpadding="0" cellspacing="0">
+ <tr>
+ <td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
+ Home</a></td>
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial5.htm">Previous
+ Page</a></td>
+ <td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
+ Outline</a></td>
+ <td width="139" valign="middle" align="center" height="25"><a
href="index.htm">Next
+ Page</a></td>
+ </tr>
+ </table>
+ <br>
+ <table width="630" border="0" cellpadding="0" cellspacing="0"
bgcolor="#ffffee" height="1707">
+ <tr>
+ <td height="3515" valign="top">
+ <p align="left"><font face="Verdana, Arial, Helvetica, sans-serif"
size="+2"><a name="oav"></a>5.0
+ Attributes, Variables, & Functions</font></p>
+ <p align="left"><font face="Verdana, Arial, Helvetica, sans-serif"
size="+2"><a name="attr"></a>5.1
+ Attributes</font></p>
+ <p>It's time to say it again. "Everything in Prothon is an
object".
+ So what exactly is an object? We know objects hold binary data like
+ integers and strings. Creating objects that hold binary data can be
+ done only by C code modules and we won't cover those in this
tutorial.
+ </p>
+ <p>Objects can also hold other objects of any type. I'm not talking
about
+ containers like lists and dictionaries. Those are specialized
objects
+ just for containment. I'm talking about all objects. Every object,
whether
+ it be an integer, string, or even a vanilla object with no type, can
+ hold other objects called attributes.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="attrkey"></a></font>So
+ objects are things that can hold binary data and attributes.
Attributes
+ are stored in an object much like dictionaries hold objects. They
are
+ stored with a key, but the attribute's keys can't be just any old
immutable
+ object as in a dictionary. In an attribute the key must be a legal
Prothon
+ symbol, like "x", or "hasKey_?".</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="symbol"></a></font>A
+ Prothon symbol can be any combination of the digits 0 to 9, the
letters
+ a to z, A to Z, and the underbar ( _ ). It cannot start with a
digit.
+ It may also optionally have a single exclamation mark ( ! ) or
question
+ mark ( ? ) at the end.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="period"></a></font>If
+ you have an object stored in a variable, then you can access the
attributes
+ of that object in a simple way using the period operator. If there
is
+ an object in x and there is an object that is an attribute of x with
+ the key "y", then you can just say "y is an attribute
+ of "x" and you can access it with "x.y".</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="attrass"></a></font>Just
+ like dictionaries, you can add new attributes or replace an existing
+ one by simply using using an assignment statement. x.y = 1 will
create
+ a new attribute y or replace an old one. Also, you can delete an
attribute
+ with the "del" delete command just like dictionaries.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="vsw"></a>5.2
+ Variables, Scope, & With</font></p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="main"></a></font>When
+ you run a Prothon source file, there is a special object called a
module
+ created. We will learn more about modules later. This module, called
+ "Main1", has attributes as all objects are capable of.
It's
+ attributes are special in that they are the "variables" of
+ the code that runs at the main level of the code. So if the first
line
+ of a source file says "x=1", you are really saying
"Main1.x
+ = 1".</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="attr"></a></font>Every
+ variable in all Prothon code is an attribute of some object. So
variables
+ and attributes are the same thing. When you use variables though,
quite
+ often the object that the variable is an attribute of is hidden and
+ it sometimes takes special knowledge of the rules to figure out what
+ that object is. This object that holds variables is called a
"scope
+ object" because it holds the variables for a certain scope of
the
+ code. A scope is something like the main level, the inside of a
function,
+ etc</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="with"></a></font>Prothon
+ has a special "with" statement just to set the current
scope
+ object. This is convenient for when you are about to work on one
object
+ extensively and want to save typing and to concentrate on that
object.
+ Later you will see something "with" is very useful for.
Here
+ is an example for now:</p>
+ <pre>>>> x = [1]
+[1]
+>>> with x:
+... a=1
+...
+>>> print x.a
+1
+>>></pre>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="funcdef"></a>5.3
+ Functions & the Def Statement</font></p>
+ <p>A function allows you to factor out code to reuse in multiple
places
+ and to abstract a function into a higher-level concept to call.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="func"></a></font>Prothon
+ is a dynamic language, which means you define the functions at
run-time,
+ not during compile time in advance. Once again, "everything is
+ an object" so functions are objects also. You create a function
+ object by using the "def statement. A function definition
consists
+ of the code to run, the parameters to pass in when the function
starts
+ and the value to return when the function ends. </p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="def"></a></font>The
+ def statement form is "def name(params): body". The name
is
+ the variable that will hold the new function object being created,
just
+ as if the name was on the left side of an assignment statement (name
+ = function). The body is the body of code that is executed just as
in
+ the "if", "for", and other statements. Params is
+ the list of variable names that the incoming parameters will be
assigned
+ to when the function is first started. These are called the formal
parameters
+ as opposed to the actual parameters that are in the function call.
</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="funcform"></a></font>Function
+ calls look similar to the definition of a function. They have the
form
+ "name(params)" where name is the variable holding the
function
+ object and params are the actual parameters to be passed to the
formal
+ parameters in the function definition. Let's look at some
examples:</p>
+ <pre># Prothon source file tut8.pr
+
+def func1(x):
+ print "x is",x
+print func1 # func1 is an object that hasn't run
+func1(99) # now it runs</pre>
+ <p>This is the output of the program: </p>
+ <pre><func:93c120>
+x is 99</pre>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="pos"></a></font>Prothon
+ has some very sophisticated methods for matching the actual
parameters
+ to the formal parameters. The simplest method is positional
matching.
+ If func is defined as func(x,y,z) and is called as func(1,2,3) then
+ x=1, y=2, and z=3 after the function starts. </p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="defval"></a></font>The
+ next param passing trick is the use of default values, also known as
+ optional params. If the formal param in the function definition has
+ the form "name = value", then that param can be missing in
+ the actual params and the default value will be used instead. If the
+ func is defined as func(x, y=11, z=12) and it is called as func(1,2)
+ then x=1, y=2, and z=12 inside the function. Note that the formal
params
+ with defaults must follow the params without defaults to avoid
ambiguities.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="namematch"></a></font>The
+ third param technique is to match the formal and actual params by
keyword
+ instead of by position. To do this, you use the form "name =
value"
+ in the actual param in the function call. This allows you to place
the
+ actual params in any order and it makes the call self-documenting.
If
+ the func is defined as func(x,y,z) and it is called as func(y=1,
z=2,
+ x=3), then x=3, y=1, and z=2 inside the function.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="starvar"></a></font>Finally,
+ there is a very powerful technique that allows a variable number of
+ parameters to be passed to or accepted into a function. If a formal
+ parameter list ends in "*var" then all actual positional
parameters
+ "left over" that haven't been assigned to formal
positional
+ parameters are put into a list named var. Likewise, if the formal
list
+ ends with a "**var" then all the given actual named
parameters
+ that don't match any parameters in the formal list are put into a
dictionary
+ named var with the name as the key and the actual value as the
value.
+ If you put both "*var1, **var2" into the formal list then
+ all paramaters are guaranteed to be captured. </p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="actstarvar"></a></font>In
+ the other direction, you can pass *var1 and **var2 as actual
parameters
+ in a call where var is a list of actual positional parameters and
var2
+ is a dictionary of named actual parameters. This allows you to
calculate
+ an arbitrary number of parameters to pass to a function. </p>
+ <p>Note that combining these two directions allows you to accept every
+ possible set of parameters in a function by using the definition
func1(*args,
+ **kwargs) and then passing on that arbitray set of parameters to
another
+ function with the call func2(*args, **kwargs).</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="sampleparms"></a></font>Here
+ are some samples of parameter passing:</p>
+ <pre># Prothon source file tut9.pr
+
+def func(x,y=1,*args,**kwargs):
+ print 'x:',x,'y:',y
+ for arg in args:
+ print 'arg:',arg
+ for kwarg in kwargs.items():
+ print 'kwarg:', kwarg[0], kwarg[1]
+ print
+
+func(0)
+func(1,2)
+func(1,x=11,y=22,z=33)
+func(1,2,3,4)
+func(1,2,3,4,a=11,b=22,c=33)</pre>
+ <p>Here is the output:</p>
+ <pre>x: 0 y: 1
+
+x: 1 y: 2
+
+x: 1 y: 22
+kwarg: x 11
+kwarg: z 33
+
+x: 1 y: 2
+arg: 3
+arg: 4
+
+x: 1 y: 2
+arg: 3
+arg: 4
+kwarg: a 11
+kwarg: b 22
+kwarg: c 33</pre>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="localscope"></a></font>So
+ what happens to the parameters when they are passed in to the
function?
+ When the function starts, a new scope object is created from scratch
+ called the "local scope". This is where the local
variables
+ of the function are stored. After the local scope object is created,
+ the actual parameters are copied into that scope object just as if
an
+ assignment statement happened for each parameter. </p>
+ <p>Let's say that the scope object is called "local" (it's
not
+ really, it doesn't have a name). Then a function defined as func(a,
+ b, c) and called as func(1, 'a', obj) would cause parameter passing
+ that is equivalent to this code:</p>
+ <pre>local.a = 1
+local.b = 'a'
+local.c = obj</pre>
+ <p>Then inside the function, any reference to a, b or c will default
to
+ the "local scope" and actually use local.a, local.b and
local.c.
+ </p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="passref"></a></font>Notice
+ that the last parameter passed was an obj that might be mutable.
Just
+ as in an assignment, the thing passed is just a reference to the
obj,
+ not a copy of the object. This means that the variable obj outside
of
+ the function is the same exact object as the c object inside the
function.
+ If you make a change to c then obj will change also. This cannot
happen
+ with a or b since numbers and strings are immutable and cannot be
changed.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="noneobj"></a></font>Function
+ always return a value to the caller. In the functions we have been
looking
+ at they have been returning the default value of None. None is a
special
+ unique object like the True and False objects. Speaking of True and
+ False, None.bool_() returns False so None is False in expressions
and
+ "if" and "while" statements.</p>
+ <p><font face="Verdana, Arial, Helvetica, sans-serif" size="+2"><a
name="rtrnstmt"></a></font>To
+ return something other than None, or to stop executing a function
somewhere
+ other than at the end, you use the "return" statement.
This
+ statement is somewhat like "break" in that it stops
execution,
+ but "return" returns from the function block of code no
matter
+ how deeply nested. If return has a parameter, that is returned as
the
+ return value of the function, else the None object is returned.</p>
+ <pre>>>> def squared(x):
+... return x*x
+...
+>>> squared(3)
+9
+>>></pre>
+ </td>
+ </tr>
+ </table>
+ <table width="630" border="0" cellpadding="0" cellspacing="0">
+ <tr>
+ <td width="114" height="25" valign="top"> <a
href="http://prothon.org";>Prothon
+ Home</a></td>
+ <td width="194" valign="middle" align="center" height="25"><a
href="tutorial5.htm">Previous
+ Page</a></td>
+ <td width="183" valign="middle" align="center" height="25"><a
href="index.htm">Tutorial
+ Outline</a></td>
+ <td width="139" valign="middle" align="center" height="25"><a
href="index.htm">Next
+ Page</a></td>
+ </tr>
+ </table>
+</div>
+</body>
+</html>
Added: trunk/pr/tutorial/tut8.pr
===================================================================
--- trunk/pr/tutorial/tut8.pr 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/pr/tutorial/tut8.pr 2004-05-15 05:44:17 UTC (rev 490)
@@ -0,0 +1,8 @@
+
+# Prothon source file tut8.pr
+
+def func1(x):
+ print "x is",x
+print func1 # func1 is an object that hasn't run
+func1(99) # now it runs
+
Added: trunk/pr/tutorial/tut9.pr
===================================================================
--- trunk/pr/tutorial/tut9.pr 2004-05-14 22:36:02 UTC (rev 489)
+++ trunk/pr/tutorial/tut9.pr 2004-05-15 05:44:17 UTC (rev 490)
@@ -0,0 +1,17 @@
+
+# Prothon source file tut9.pr
+
+def func(x,y=1,*args,**kwargs):
+ print 'x:',x,'y:',y
+ for arg in args:
+ print 'arg:',arg
+ for kwarg in kwargs.items():
+ print 'kwarg:', kwarg[0], kwarg[1]
+ print
+
+func(0)
+func(1,2)
+func(1,x=11,y=22,z=33)
+func(1,2,3,4)
+func(1,2,3,4,a=11,b=22,c=33)
+
|
