mf_callersversion.hlp

是一个经济学管理应用软件 很难找的 但是经济学学生又必须用到

{smcl}
{* 11mar2005}{...}
{cmd:help mata callersversion()}
{hline}
{* index version control}{...}
{* index callersversion()}{...}

{title:Title}

{p 4 4 2}
{bf:[M-5] callersversion() -- Obtain version number of caller}


{title:Syntax}

{p 8 12 2}
{it:real scalar} 
{cmd:callersversion()}


{title:Description}

{p 4 4 2}
{cmd:callersversion()} returns the version set by the caller 
(see {bf:{help m2_version:[M-2] version}}),
or if the caller did not set the version, it returns the version of Stata
under which the caller was compiled.


{title:Remarks}

{p 4 4 2}
{cmd:callersversion()} is how {bf:{help m2_version:[M-2] version}}
is made to work.
For instance, say you have written function 

		{it:real matrix} {cmd:useful(}{it:real matrix A}{cmd:,} {it:real scalar k}{cmd:)}

{p 4 4 2}
and assume that {cmd:useful()} aborts with error if {it:A} is void.
You wrote {cmd:useful()} in the days of Stata 9.  For Stata 10, you want 
to change {cmd:useful()} so that it returns J(0,0,.) if {it:A} is 
void, but you want to maintain the current behavior for old Stata 9
callers and programs.  You do that as follows:

	{cmd}real matrix useful(real matrix A, real scalar k)
	{
		...

		if (callersversion()>=10) {
			if (rows(A)==0 | cols(A)==0) return(J(0,0,.))
		}
		...
	}{txt}


{title:Conformability}

    {cmd:callersversion()}:
	   {it:result}:  1 {it:x} 1

	
{title:Diagnostics}

{p 4 4 2}
None.


{title:Source code}

{p 4 4 2}
Function is built-in.


{title:Also see}

{p 4 13 2}
Manual:  {hi:[M-5] callersversion()}

{p 4 13 2}
Online:  help for 
{bf:{help m2_version:[M-2] version}};
{bf:{help m4_programming:[M-4] programming}}
{p_end}