.Dd January 12, 2020
.Os libzt 0.3.1
.Dt ZT_FALSE 3 PRM
.Sh NAME
.Nm ZT_FALSE ,
.Nm zt_false
.Nd construct a claim that a value is false
.Sh SYNOPSIS
.In zt.h
.Bd -literal
#define ZT_FALSE(value) \\
  zt_false( \\
    ZT_CURRENT_LOCATION(), \\
    zt_pack_boolean((value), #value)) \\
.Ed
.Ft zt_claim
.Fo zt_false
.Fa "zt_location location"
.Fa "zt_value value"
.Fc
.Sh DESCRIPTION
.Fn zt_false
constructs a claim that a given value is false. It should be used through the
macro
.Fn ZT_FALSE ,
which passes source code location and packs argument.
.Pp
.Fn zt_false
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_FALSE
evaluates
.Em value
only once.
.Sh RETURN VALUES
Both the macro and the function return a claim structure with the right
attributes set. The returned claim is usually passed to
.Fn zt_check
or to
.Fn zt_assert .
.Sh SEE ALSO
.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_check 3 ,
.Sh HISTORY
The
.Fn ZT_FALSE
macro and the
.Fn zt_false
function first appeared in libzt 0.1
.Sh AUTHORS
.An "Zygmunt Krynicki" Aq Mt me@zygoon.pl