tasks a-s

Task/Scope-Function-names-and-labels/0DESCRIPTION

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+The task is to explain or demonstrate the levels of visibility of function names and labels within the language.
+
+;See also
+* [[Variables]] for levels of scope relating to visibility of program variables
+* [[Scope modifiers]] for general scope modification facilities

Task/Scope-Function-names-and-labels/1META.yaml

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+---
+category:
+- Scope
+note: Basic language learning

Task/Scope-Function-names-and-labels/AWK/scope-function-names-and-labels.awk

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+# This program outputs a greeting
+BEGIN {
+  sayhello()    # Call the function defined below
+  exit
+}
+
+function sayhello {
+   print "Hello World!"    # Outputs a message to the terminal
+}

Task/Scope-Function-names-and-labels/BASIC/scope-function-names-and-labels-1.basic

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+GOTO 50: REM THIS WILL WORK IMMEDIATELY

Task/Scope-Function-names-and-labels/BASIC/scope-function-names-and-labels-2.basic

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+10 DEF FN S(A)=A*A
+20 PRINT FN S(2): REM THIS WILL WORK
+30 PRINT FN C(2): REM CALLING A FUNCTION PRIOR TO DEFINITION MAY NOT WORK
+40 GOSUB 9000
+50 PRINT FN C(2): REM THIS WILL WORK
+60 END
+9000 DEF FN C(A)=A*A*A
+9999 RETURN

Task/Scope-Function-names-and-labels/Perl-6/scope-function-names-and-labels.pl6

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+# call a routine before it has been defined
+say log();              # prints: outer
+
+# define a subroutine that overrides a CORE function
+sub log { 'outer' };
+{
+    # redefine the subroutine in this block
+    sub log { 'inner' };
+    {
+        # redefine the subroutine yet again
+        sub log { 'way down inside' };
+
+        # call it within this block
+        say log();                 # prints: way down inside
+
+        # call it from the block one level out
+        say &OUTER::log();         # prints: inner
+
+        # call it from the block two levels out
+        say &OUTER::OUTER::log();  # prints: outer
+
+        # call it from the outermost block
+        say &UNIT::log();          # prints: outer
+
+        # call a subroutine that is post declared in outermost scope
+        outersub()
+    }
+
+    {
+        # subroutine in an inner block that doesn't redefine it
+        # uses definition from nearest enclosing block
+        say log();      # prints: inner
+    }
+    # call it within this block
+    say log();          # prints: inner
+
+    # call it from the block one level out
+    say &OUTER::log();  # prints: outer
+}
+
+sub outersub{
+    # call subroutine within this block - gets outer sub
+    say log();          # prints: outer
+
+    # call subroutine from the scope of the callers block
+    say &CALLER::log(); # prints: way down inside
+
+    # call subroutine from the outer scope of the callers block
+    say &CALLER::OUTER::log(); # prints: inner
+
+    # call the original overridden CORE routine
+    say &CORE::log(e);  # prints: 1 ( natural log of e )
+}

Task/Scope-Function-names-and-labels/REXX/scope-function-names-and-labels.rexx

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+/*REXX program demonstrates use of labels and a CALL. */
+zz=4
+signal do_add
+ttt=sinD(30)   /*this REXX statement is never executed.*/
+
+do_add:        /*coming here from the SIGNAL statement.*/
+
+say 'calling the sub add.2.args'
+call add.2.args 1,7
+say 'sum=' result
+exit           /*stick a fork in it, 'cause we're done.*/
+
+add.2.args: procedure; parse arg x,y;    return x+y

Task/Scope-Function-names-and-labels/Tcl/scope-function-names-and-labels.tcl

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+doFoo 1 2 3;    # Will produce an error
+
+proc doFoo {a b c} {
+    puts [expr {$a + $b*$c}]
+}
+doFoo 1 2 3;    # Will now print 7 (and will continue to do so until doFoo is renamed or deleted

Task/Scope-Function-names-and-labels/UNIX-Shell/scope-function-names-and-labels.sh

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+#!/bin/sh
+multiply 3 4    # This will not work
+echo $?    # A bogus value was returned because multiply definition has not yet been run.
+
+multiply() {
+  return `expr $1 \* $2`    # The backslash is required to suppress interpolation
+}
+
+multiply 3 4    # Ok. It works now.
+echo $?         # This gives 12

Task/Scope-Function-names-and-labels/ZX-Spectrum-Basic/scope-function-names-and-labels.zx

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+9000 REM The function is immediately visible and usable
+9010 DEF FN s(x)=x*x
+
+PRINT FN s(5): REM This will work immediately
+GO TO 50: REM This will work immediately