Function _conEvalMacro() | Xbase++

Executes a macro expression in a container.

XPPAPIRET _conEvalMacro(ContainerHandle chres,
                        ContainerHandle chcMacro);

ContainerHandle chres

Handle of a container for the result of the macro expression.

ContainerHandle chcMacro

String container which contains a macro expression. Any expression is allowed which the Xbase++ macro operator (&) can execute.

When the passed string container does not have a valid macro expression, an error value is returned (XPP_ERR_...). If an error occurs during execution of the expression, the error code block is called. Note:If the error code block causes a BREAK, the return value of _conEvalMacro() is XPP_ERR_BREAK. If the error can be rectified by the error code block, the return value is NULL.

Using this function, dynamically created expressions can be evaluated. For example, initialized multidimensional arrays and code blocks can be created, functions with constant parameters can be called and PRIVATE and PUBLIC variables can be accessed.

It should be noted that the runtime execution of macros is not very efficient, since the expression must first be translated each time the macro is executed. If an expression is to be executed frequently, it is recommended that a code block will be created.

/* 
Execute a string as a macro expression 
*/ 
#include <xppcon.h> 

XPPAPIRET        xr 
ContainerHandle  chsMacro, chxResult; 

chsMacro = _conPutC( NULLCONTAINER, "1+1" ); 
chxResult = _conNew( NULLCONTAINER ); 

if (chsMacro != NULLCONTAINER  &&  chxResult != NULLCONTAINER) 
{ 
xr = _conEvalMacro( chxResult, chsMacro ); 
if (xr == 0) 
{ 
   /* The result should be a numeric */ 
   if( XPP_IS_NUM( _conType( chxResult ) ){ 
      /* The value should be 2*/ 
   } 
} 
else 
{ 
   /* error handling ... */ 
} 
_conRelease( chsMacro ); 
_conRelease( chResult ); 
}

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Function _conEvalMacro() Foundation