select ifs, pick ifs

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Function Names

select ifs, pick ifs

Description

These two functions act like a cascaded arrangement of multiple select if resp. pick if function calls. The first parameter contains the default value. Following this, the even-numbered parameters take boolean expressions, for example from comparisons. If the outcome is true, then the value specified in the parameter is taken over, otherwise the next boolean expression wil be checked. If all boolean expressions were false, then the defalt value will be returned.

select will calculate all function parameters
pick will calculate the 2nd function parameter followed by the 3rd parameter if true, otherwise it will calculate the 4th parameter, and so forth. Long story short, only the parameter values needed will be calculated and this save a lot of processing time especialy for heavy expressions.

Call as: procedure or function

Restrictions

Indirect parameter passing is disabled

Parameter count

3, 5, 7, etc.

Parameters

No.TypeDescription
1
input
all types Default value

Applicable to select ifs: This value will be returned if all boolean values provided in the even-numbered function paramters are false.

Alt. 1
code
expression
:string
Default expression

Applicable to pick ifs: This expression will be calculated and the value returned if all boolean values provided in the even-numbered function paramters are false.

2, 4, ...
input
boolean Boolean value

Applicable to select ifs: This value is true, then the value in the next function parameter will be returned.

Alt. 2, 4, ...
code
expression
:string
Boolean expression

Applicable to pick if: If this expression calculated returns true, then the expression in the next function parameter will be calculated and the value returned.

3, 5, ...
input
all types Selected value if true

Applicable to select ifs: This value will be returned if true is provided in the previous function parameter.

Alt. 3, 5, ...
code
expression
:string
Selected expression if true

Applicable to pick if: This expression will be calculated and returned if true is provided in the previous function parameter.

Return value

TypeDescription
all types Selected value

Examples

       echo("Demonstrate 'select ifs':");
       a[] = 1; b[] = 2; c[] = 3;
       x[] = select ifs( echo("Others "), (a[]++=0), echo("1st "), (b[]++ = 2), echo("2nd "), (c[]++ = 3), echo("3rd ") );
       // All parameter will be calculated.

       echo("a..c[] = ", a[], " ", b[], " ", c[],".  Result is ", x[] );

       echo(new line, "Demonstrate 'pick ifs':");
       a[] = 1; b[] = 2; c[] = 3;
       x[] = pick ifs( echo("Others "), (a[]++=0), echo("1st "), (b[]++ = 2), echo("2nd "), (c[]++ = 3), echo("3rd ") );
       // The first two conditions will be calculated as well as 'echo("2nd ")'.

       echo("a..c[] = ", a[], " ", b[], " ", c[],".  Result is ", x[] );

Output

Demonstrate 'select ifs':
Others
1st
2nd
3rd
a..c[] = 2 3 4.  Result is 2nd


Demonstrate 'pick ifs':
2nd
a..c[] = 2 3 3.  Result is 2nd

Try it yourself: Open LIB_Function_select_ifs.b4p in B4P_Examples.zip. Decompress before use.

See also

select if
pick if
select by value
pick by value