[#BloombergLP-balcl-Constraint]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/balcl.adoc[balcl]::Constraint
:relfileprefix: ../../
:mrdocs:

This `struct` provides a namespace that defines the types used to impose user‐defined constraints on values associated with command‐line options. One type is defined for each scalar type defined in `balcl::OptionType` except for `bool`.

== Synopsis

Declared in `<balcl_constraint.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
struct Constraint;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balcl/Constraint/CharConstraint.adoc[`CharConstraint`] 
| Functor type that validates `char` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/DateConstraint.adoc[`DateConstraint`] 
| Functor type that validates `bdlt::Date` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/DatetimeConstraint.adoc[`DatetimeConstraint`] 
| Functor type that validates `bdlt::Datetime` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/DoubleConstraint.adoc[`DoubleConstraint`] 
| Functor type that validates `double` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/Int64Constraint.adoc[`Int64Constraint`] 
| Functor type that validates `Int64` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/IntConstraint.adoc[`IntConstraint`] 
| Functor type that validates `int` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/StringConstraint.adoc[`StringConstraint`] 
| Functor type that validates `bsl::string` option values; see `TimeConstraint`.
| xref:BloombergLP/balcl/Constraint/TimeConstraint.adoc[`TimeConstraint`] 
| Functor type that validates `bdlt::Time` option values.
|===



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