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<span style="font-size:120%; color:black"><b><section begin=dpl_desc/>Get Call Stack<section end=dpl_desc/></b></span>
{{Template:System:CallStack subtitle}}
[[Category:System methods|CallStack function]]
The <var>CallStack</var> shared function returns a <var>[[Stringlist_class|Stringlist]]</var> containing information about the current call stack: information about the caller of the current method or subroutine, the caller of that caller, and so on.
[[Category:System/Subsystem methods]]
<!--DPL?? Category:System methods|CallStack function: Get Call Stack-->
<p>
CallStack is a member of the [[System class]].
</p>


This shared function returns a Stringlist containing information about the current
==Syntax==
call stack: information about the caller of the current method or subroutine,
{{Template:System:CallStack syntax}}
the caller of that caller, and so on.
===Syntax terms===
<table class="syntaxTable">
<tr><th>%sl</th><td>A <var>Stringlist</var> object to be set to reference the object that contains information about the current call stack.  The first item in the <var>Stringlist</var> refers to the immediate caller of the current method or subroutine; a second item refers to the caller of that caller, if any; and so on.</td></tr>
<tr><th><var class="nobr">%(System)</var></th><td>The class name in parentheses denotes a [[Notation conventions for methods#Shared methods|shared]] method.</td></tr>
</table>


The CallStack method is available in ''Sirius Mods'' 7.2 and later.
==Usage Notes==
===Syntax===
<ul>
  %callList = %(system):CallStack
<li><var>CallStack</var> returns the name of the procedure and the line within the procedure that made the calls of the current method or subroutine. Generally, each returned <var>Stringlist</var> item has the name of the file containing the calling procedure at positions one through eight, followed by a blank, followed by the name of the calling procedure, followed by a blank, followed by the line number within the calling procedure.
====Syntax Terms====
<p class="note"><b>Note:</b> The call stack information returned by <var>CallStack</var> refers to the (names of and line numbers in) procedures that contain the calls to the current method or subroutine, ''not'' to (names of and line numbers in) the current subroutine or method.</p></li>
<dl>
<dt><i><b>%callList</b></i>
<dd>A Stringlist object to be set to reference the object that contains information
about the current call stack.
The first item in the Stringlist refers to the immediate caller of
the current method or subroutine; a second item refers to the caller of that caller,
if any; and so on.
<dt>%(system)
<dd>The class name in parentheses denotes a shared method.


</dl>
<li>For method or subroutine calls that were entered at command level (not inside a procedure), the <var class="term">%sl</var> item will contain a single asterisk character (<tt>*</tt>).
===Usage Notes===
If <var>CallStack</var> cannot determine the location of the call, the <var class="term">%sl</var> item associated with a call will be null (zero-length). If not issued from within a method or subroutine, <var>CallStack</var> will return an empty (zero-item) Stringlist.</li>
<ul>
 
<li>The CallStack method returns the name of the
<li>For <var>CallStack</var> to determine the location of a method or subroutine call, source line information must be collected at compile time. Either you must set the <var>[[SIRFACT_parameter|SIRFACT]]</var> system parameter's X'01' bit, or the request must be compiled with the <var class="product">Model 204</var> <var>DEBUGUL</var> user parameter set to a non-zero value.
procedure and the line within the procedure that made the calls of the current
<p>
method or subroutine.
To use the <var>SIRFACT</var> system parameter, your site must be authorized for <var class="product">[[SirFact]]</var>. Using the <var>DEBUGUL</var> user parameter increases the <var>QTBL</var> and (to a lesser degree) <var>VTBL</var> requirements for a compiled request.</p></li>
Generally, each returned Stringlist item has the name of the file containing
the calling procedure at positions one through eight, followed by a blank,
followed by the name of the calling procedure, followed by a blank, followed
by the line number within the calling procedure.
'''Note:'''
The call stack information returned by the CallStack method refers to the
(names of and line numbers in)
procedures that contain the calls to the current method or subroutine,
''not'' to (names of and line numbers in) the current
subroutine or method.
<li>For method or subroutine calls that were entered at command level (not inside a
procedure), the ''%callList'' item will contain a single asterisk
character (<tt>*</tt>).
If CallStack cannot determine the location of the call, the ''%callList''
item associated with a call will be null (zero-length).
If not issued from within a method or subroutine, CallStack will
return an empty (zero-item) Stringlist.
<li>For CallStack to determine the location of a method or subroutine call,
source line information must be collected at compile time.
Either you must set the SIRFACT system parameter's X'01' bit, or the
request must be compiled with the DEBUGUL user parameter set to a non-zero value.


To use the SIRFACT system parameter, your site must be authorized for [[SirFact]].
<li>The <var>CallStack</var> method is intended to be used for problem diagnosis and, perhaps, for logging and auditing. Using it to affect method or subroutine behavior by causing a method or subroutine to behave differently depending on its caller is <b><i>extremely</i></b> poor technique, and it cannot be discouraged strongly enough. </li>
Using the DEBUGUL user parameter increases
the QTBL and (to a lesser degree) VTBL requirements for a compiled request.
<li>The CallStack method is intended to be used for problem diagnosis and, perhaps,
for logging and auditing.
Using it to affect method or subroutine behavior by causing a method or subroutine
to behave differently depending on its caller is '''extremely''' poor technique,
and it cannot be discouraged strongly enough.
</ul>
</ul>
===Example===


In the MYTAX.UL procedure,
==Examples==
the computeTax1 subroutine is called by the computeTax2 subroutine
In the MYTAX.UL procedure, the computeTax1 subroutine is called by the computeTax2 subroutine at line 146. If you issue the following statements from within computeTax1:
at line 146.
<p class="code">%callList is object stringlist
If you issue the following statements from within computeTax1:
%callList = %(system):callStack
<pre style="xmp">
%callList:[[Print_(Stringlist_function)|print]]
    %callList is object Stringlist
</p>
    %callList = %(system):CallStack
The result is something like the following:
    %callList:Print
<p class="output">MYPROC  MYTAX.UL 193
</pre>
MYPROC  MYTAX.UL 146
</p>


The result is something like the following:
==See Also==
<pre style="xmp">
{{Template:System:CallStack footer}}
    MYPROC  MYTAX.UL 193
    MYPROC  MYTAX.UL 146
</pre>

Latest revision as of 19:45, 2 July 2014

Current call stack description (System class)

The CallStack shared function returns a Stringlist containing information about the current call stack: information about the caller of the current method or subroutine, the caller of that caller, and so on.

Syntax

%sl = %(System):CallStack

Syntax terms

%slA Stringlist object to be set to reference the object that contains information about the current call stack. The first item in the Stringlist refers to the immediate caller of the current method or subroutine; a second item refers to the caller of that caller, if any; and so on.
%(System)The class name in parentheses denotes a shared method.

Usage Notes

  • CallStack returns the name of the procedure and the line within the procedure that made the calls of the current method or subroutine. Generally, each returned Stringlist item has the name of the file containing the calling procedure at positions one through eight, followed by a blank, followed by the name of the calling procedure, followed by a blank, followed by the line number within the calling procedure.

    Note: The call stack information returned by CallStack refers to the (names of and line numbers in) procedures that contain the calls to the current method or subroutine, not to (names of and line numbers in) the current subroutine or method.

  • For method or subroutine calls that were entered at command level (not inside a procedure), the %sl item will contain a single asterisk character (*). If CallStack cannot determine the location of the call, the %sl item associated with a call will be null (zero-length). If not issued from within a method or subroutine, CallStack will return an empty (zero-item) Stringlist.
  • For CallStack to determine the location of a method or subroutine call, source line information must be collected at compile time. Either you must set the SIRFACT system parameter's X'01' bit, or the request must be compiled with the Model 204 DEBUGUL user parameter set to a non-zero value.

    To use the SIRFACT system parameter, your site must be authorized for SirFact. Using the DEBUGUL user parameter increases the QTBL and (to a lesser degree) VTBL requirements for a compiled request.

  • The CallStack method is intended to be used for problem diagnosis and, perhaps, for logging and auditing. Using it to affect method or subroutine behavior by causing a method or subroutine to behave differently depending on its caller is extremely poor technique, and it cannot be discouraged strongly enough.

Examples

In the MYTAX.UL procedure, the computeTax1 subroutine is called by the computeTax2 subroutine at line 146. If you issue the following statements from within computeTax1:

%callList is object stringlist %callList = %(system):callStack %callList:print

The result is something like the following:

MYPROC MYTAX.UL 193 MYPROC MYTAX.UL 146

See Also

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