.Dd January 12, 2020
.Os libzt 0.3.1
.Dt ZT_TRUE 3 PRM
.Sh NAME
.Nm ZT_TRUE ,
.Nm zt_true
.Nd construct a claim that a value is true
.Sh SYNOPSIS
.In zt.h
.Bd -literal
#define ZT_TRUE(value) \\
  zt_true( \\
    ZT_CURRENT_LOCATION(), \\
    zt_pack_boolean((value), #value)) \\
.Ed
.Ft zt_claim
.Fo zt_true
.Fa "zt_location location"
.Fa "zt_value value"
.Fc
.Sh DESCRIPTION
.Fn zt_true
constructs a claim that a given value is true. It should be used through the
macro
.Fn ZT_TRUE ,
which passes source code location and packs argument.
.Pp
.Fn zt_true
can be used to check custom properties by calling arbitrary verification logic.
The disadvantage of this approach is that on failure, the error message cannot
precisely explain the problem.
.Sh IMPLEMENTATION NOTES
.Fn ZT_TRUE
evaluates
.Em value
only once.
.Sh RETURN VALUES
Both the macro and the function return a
.Nm zt_claim
structure with the appropriate attributes set. The returned claim is usually
passed to
.Fn zt_check
or to
.Fn zt_assert .
.Sh SEE ALSO
.Xr zt_assert 3 ,
.Xr zt_check 3 ,
.Xr zt_claim 3 ,
.Xr ZT_CMP_BOOL 3 ,
.Xr ZT_CMP_RUNE 3 ,
.Xr ZT_CMP_CSTR 3 ,
.Xr ZT_CMP_INT 3 ,
.Xr ZT_CMP_PTR 3 ,
.Xr ZT_CMP_UINT 3 ,
.Xr ZT_FALSE 3 ,
.Xr ZT_NOT_NULL 3 ,
.Xr ZT_NULL 3
.Xr zt_value 3 ,
.Sh HISTORY
The
.Fn ZT_TRUE
macro and the
.Fn zt_true
function first appeared in libzt 0.1
.Sh AUTHORS
.An "Zygmunt Krynicki" Aq Mt me@zygoon.pl