Script variables - Revision history

Raffriff42: /* Declaring a New Variable */ move up-page etc

2017-11-12T17:36:33Z

‎Declaring a New Variable: move up-page etc

Raffriff42: tweak

2017-11-11T04:41:52Z

tweak

Raffriff42: tweak

2017-11-11T04:37:22Z

tweak

Raffriff42: typo

2017-11-11T03:14:55Z

typo

Raffriff42: add link to Colors; add "global" example

2017-11-11T03:03:16Z

add link to Colors; add "global" example

Raffriff42: formatting, links, phrasing

2017-11-10T12:48:54Z

formatting, links, phrasing

Raffriff42: add internal link anchor /global_variables/

2017-11-08T11:37:57Z

add internal link anchor /global_variables/

Raffriff42: new string examples

2016-03-13T23:22:11Z

new string examples

Raffriff42: string: tweak example code

2016-03-13T12:55:54Z

string: tweak example code

Raffriff42: string: add multi-line example, remove "The manual used to mention TeX-style quotes...''

2016-03-13T12:11:22Z

string: add multi-line example, remove "The manual used to mention TeX-style quotes...''

@@ Line 56: / Line 56: @@
 There is another type which is used internally by Avisynth - the {{Term|void}} or 'undefined' type. Its principal use is in conjunction with optional function arguments. See the [[Internal_functions/Boolean functions|Defined()]] function.
 {{HiddenAnchor|global_variables}}
@@ Line 61: / Line 73: @@
 Variables can be either {{Term|local}} (bound to the local scope of the executing script block) or {{Term|global}}. Global variables are bound to the global script environment's scope and can be accessed by all [[Internal functions]], [[User defined script functions]], [[runtime environment]] scripts and the main script also.
-To define and/or assign a value to a global variable you must precede its name with the keyword <tt>global</tt> at the left side of the assignment. The keyword is not needed (actually it is not allowed) in order to read the value of a global variable. Examples:
+To declare and/or assign a value to a global variable you must precede its name with the keyword <tt>global</tt> at the left side of the assignment. The keyword is not needed (or allowed) in order to ''read'' the value of a global variable. Examples:
-<div {{BoxWidthIndent|59|3}} >
+<div {{BoxWidthIndent|59|1}} >
   ## declaring global variables
   global canvas = [[BlankClip]](length=200, pixel_type="yv12")
@@ Line 70: / Line 82: @@
 </div>
-<div {{BoxWidthIndent|59|3}} >
+<div {{BoxWidthIndent|59|1}} >
   ## using a global variable inside a user function
   function MyFunction(clip c)
@@ Line 90: / Line 102: @@
   return MyFunction
   ## works as expected
 </div>
 </div>

@@ Line 74: / Line 74: @@
   function MyFunction(clip c)
+  {
-−
+      C
       (testbool ) ? [[FlipHorizontal]] : [[FlipVertical]]
       return Last

@@ Line 72: / Line 72: @@
 <div {{BoxWidthIndent|59|3}} >
   ## using a global variable inside a user function
   [[ColorBars]]
   [[Subtitle]]("ABCDEFG", size=Height/8, align=5)
@@ Line 77: / Line 84: @@
   testbool = true ## wrong - not global
   return MyFunction
-  ## ..."Error: I don't know what 'testbool' means"
+  ## "Error: I don't know what 'testbool' means"
   ...
   '''''global''''' testbool = true ## right
   return MyFunction
-  ## ...works as expected
+  ## works as expected
-−
- function MyFunction(clip c)
-−
-−
-     (testbool ) ? [[FlipHorizontal]] : [[FlipVertical]]
-     return Last
-−
 </div>

@@ Line 74: / Line 74: @@
   [[ColorBars]]
   [[Subtitle]]("ABCDEFG", size=Height/8, align=5)
   testbool = true ## wrong - not global
   return MyFunction
   function MyFunction(clip c)
@@ Line 83: / Line 90: @@
       return Last
+  }
 </div>

@@ Line 44: / Line 44: @@
 *{{Term|int}}
-: An integer (32 bits, signed). An integer literal is entered as a sequence of digits, optionally with a + or - at the beginning. The value can be given in ''hexadecimal'' by preceding it with a "$" character.  For example <tt>$FF</tt> as well as <tt>$ff</tt> (case does not matter) are equal to 255. See also: [[Internal_functions/Numeric_functions|Numeric Functions]].
+: An integer (32 bits, signed). An integer literal is entered as a sequence of digits, optionally with a <tt>+</tt> or <tt>-</tt> at the beginning. The value can be given in ''hexadecimal'' (often used for [[Colors|color values]]) by preceding it with a <tt>'''$'''</tt> character.  For example <tt>$FF</tt> as well as <tt>$ff</tt> (case does not matter) are equal to 255. See also: [[Internal_functions/Numeric_functions|Numeric Functions]].
 *{{Term|float}}
@@ Line 63: / Line 63: @@
 To define and/or assign a value to a global variable you must precede its name with the keyword <tt>global</tt> at the left side of the assignment. The keyword is not needed (actually it is not allowed) in order to read the value of a global variable. Examples:
 <div {{BoxWidthIndent|59|3}} >
   global canvas = [[BlankClip]](length=200, pixel_type="yv12")
   global stroke_intensity = 0.7
   ...
   global canvas = [[Overlay]](canvas, pen, opacity=stroke_intensity, mask=brush)
 </div>

@@ Line 1: / Line 1: @@
 <div style="max-width:62em" >
-''"String" redirects here. For the String() conversion function, see [[Internal_functions#String|Internal functions: String]]''
+''"String" redirects here. For the ''String()'' conversion function, see [[Internal_functions#String|Internal functions: String]]''
-''"Val" redirects here. For the Value() conversion function, see [[Internal_functions#Value|Internal functions: Value]]''
+''"Val" redirects here. For the ''Value()'' conversion function, see [[Internal_functions#Value|Internal functions: Value]]''
-This page shows how to use ''variables'' to store intermediate values for further processing in a script. It also describes the types of data that scripts can manipulate, and how ''literals'' (constants) of those types are written.
+===== Variable Names =====
-A ''variable name'' can be a character string of practically any length (more than 4000 characters in Avisynth 2.56 and later) that contains (English) letters, digits, and underscores (_), but no other characters. The name cannot start with a digit.
+A ''variable name'' may be made of (English) letters, digits, and underscores (_), but no other characters. The name cannot start with a digit. The name can be of practically any length &ndash; more than 4000 characters. Variable names are not case-sensitive.
-You may use characters from your language system codepage (locale) in strings and file names (ANSI 8 bit only, not Unicode).
+You may use characters from your language system [[wikipedia:Code_page|code page]]  (ANSI 8 bit only, not Unicode) in ''string literals'' (see below) and file names, but variable names are restricted to the [[wikipedia:ASCII#Printable_characters|ASCII characters]] <tt>A</tt>-<tt>Z</tt>, <tt>a</tt>-<tt>z</tt>, <tt>0</tt>-<tt>9</tt> and <tt>_</tt> (underscore).
 A variable's placement in an ''expression'' is determined by the [[AviSynth Syntax]].
 Variables can have a value of one of the following ''types'':
 *{{Term|clip}}
-: A video clip containing video and / or audio. A script must return a value of this type. Clips have various [[Clip_properties|properties]] that can be accessed.
+: A ''clip'' holds the video and/or audio content; all [[Frameserver|frameserving]] scripts (there are other types, such as [[Import|function library scripts]]) must return a value of type ''clip''. Clips also have [[Clip_properties|properties]], such as ''Width'', ''Height'' and ''FrameRate''.
 *{{Term|string}}
-: A sequence of characters representing text.  String literals are written as text surrounded either by <tt>"</tt>quotation marks<tt>"</tt> or by <tt>"""</tt>triple quotes<tt>"""</tt>. The text can contain any characters (including line breaks) except the terminating quotation mark or triple-quote sequence.
+: A sequence of characters representing text. String literals are written as text surrounded either by <tt>"</tt>quotation marks<tt>"</tt> or by <tt>"""</tt>triple quotes<tt>"""</tt>. The text can contain any characters (including line breaks) except the terminating quotation mark or triple-quote sequence.
 <div {{BoxWidthIndent|42|3}} >
   [[ColorBars]]
@@ Line 55: / Line 58: @@
 {{HiddenAnchor|global_variables}}
 Variables can be either {{Term|local}} (bound to the local scope of the executing script block) or {{Term|global}}. Global variables are bound to the global script environment's scope and can be accessed by all [[Internal functions]], [[User defined script functions]], [[runtime environment]] scripts and the main script also.
-To define and/or assign a value to a global variable you must precede its name with the keyword <tt>global</tt>  at the left side of the assignment. The keyword is not needed (actually it is not allowed) in order to read the value of a global variable. Examples:
+To define and/or assign a value to a global variable you must precede its name with the keyword <tt>global</tt> at the left side of the assignment. The keyword is not needed (actually it is not allowed) in order to read the value of a global variable. Examples:
+<div {{BoxWidthIndent|59|3}} >
   global canvas = [[BlankClip]](length=200, pixel_type="yv12")
   global stroke_intensity = 0.7
   ...
   global canvas = [[Overlay]](canvas, pen, opacity=stroke_intensity, mask=brush)
 To declare a variable, simply type the variable name, followed by '=' (an equals sign), followed by its initial value. The type must not be declared; it is inferred by the value assigned to it (and can actually be changed by subsequent assignments). The only place where it is allowed (though not strictly required) to declare a variable's type is in [[User_defined_script_functions|user defined script function's]] argument lists. Examples:
+<div {{BoxWidthIndent|59|3}} >
   b = false      # declare a variable 'b' of type 'bool' and initialize it to 'false'
   x = $100       # type int (initial value is in hexadecimal)
@@ Line 73: / Line 79: @@
   function my_recolor_filter(clip c, int new_color, float amount, val "userdata") { ... }
 </div>
 ----
-Back to [[AviSynth Syntax]].
+'''&larr;''' Back to [[AviSynth Syntax]].
 [[Category:AviSynth_Syntax]]
 [[Category:Scripting_Basics]]

← Older revision		Revision as of 11:37, 8 November 2017
Line 54:		Line 54:
	There is another type which is used internally by Avisynth - the {{Term\|void}} or 'undefined' type. Its principal use is in conjunction with optional function arguments. See the [[Internal_functions/Boolean functions\|Defined()]] function.		There is another type which is used internally by Avisynth - the {{Term\|void}} or 'undefined' type. Its principal use is in conjunction with optional function arguments. See the [[Internal_functions/Boolean functions\|Defined()]] function.

		+	{{HiddenAnchor\|global_variables}}
	Variables can be either {{Term\|local}} (bound to the local scope of the executing script block) or {{Term\|global}}. Global variables are bound to the global script environment's scope and can be accessed by all [[Internal functions]], [[User defined script functions]], [[runtime environment]] scripts and the main script also.		Variables can be either {{Term\|local}} (bound to the local scope of the executing script block) or {{Term\|global}}. Global variables are bound to the global script environment's scope and can be accessed by all [[Internal functions]], [[User defined script functions]], [[runtime environment]] scripts and the main script also.

@@ Line 19: / Line 19: @@
 *{{Term|string}}
-: A sequence of characters representing text.  String literals are written as text surrounded either by <tt>"</tt>quotation marks<tt>"</tt> or by <tt>"""</tt>triple quotes<tt>"""</tt>. The text can contain any characters except the terminating quotation mark or triple-quote sequence.
+: A sequence of characters representing text.  String literals are written as text surrounded either by <tt>"</tt>quotation marks<tt>"</tt> or by <tt>"""</tt>triple quotes<tt>"""</tt>. The text can contain any characters (including line breaks) except the terminating quotation mark or triple-quote sequence.
-:* To put a quotation mark inside a string, you need to use the triple-quote form. For example:
 <div {{BoxWidthIndent|42|3}} >
-  Subtitle("""AviSynth is as they say, "L33T" """)
+  [[ColorBars]]
 </div>
 <div {{BoxWidthIndent|42|3}} >
   [[ColorBars]]
-  Q=[[Internal functions#Chr|Chr]](34)
+  [[ScriptClip]]("""
-  [[Subtitle]]("AviSynth is as they say, "+Q+"L33T"+Q
+ #comment
-  \ , align=5)
+  [[Subtitle]]("Current frame = " + [[Internal_functions#String|String]]([[Runtime_environment#Special_runtime_variables_and_functions|current_frame]]),
   """)
 </div>
 *{{Term|int}}

@@ Line 25: / Line 25: @@
 </div>
 :* Alternatively, you can use <tt>“</tt>curly-quotes<tt>”</tt> inside the string instead of straight quotes to get around this limitation.
-:* Embedded quotes may also be included with <tt>[[Internal functions#Chr|Chr]](34)</tt> .
+:* Embedded quotes may also be included with <tt>[[Internal functions#Chr|Chr]](34)</tt>; see the next example.
-:* Triple-quoted strings also support embedded line breaks, which comes in very handy for [[ScriptClip]] and [[Internal functions#Eval|Eval]]. For example:
+:* Triple-quoted strings also support embedded line breaks. For example:
 <div {{BoxWidthIndent|42|3}} >
   [[Internal functions#Eval|Eval]]("""
   #comment
   [[ColorBars]]
-  [[Subtitle]]("AviSynth is as they say, "+[[Internal functions#Chr|Chr]](34)+"L33T"+Chr(34)
+ Q=[[Internal functions#Chr|Chr]](34)
   \ , align=5)
   """)