The BOOST_PP_LPAREN_IF macro conditionally expands to a left parenthesis.

#### Usage

BOOST_PP_LPAREN_IF(cond)

#### Arguments

cond
  The condition that determines if a the macro expands to a left parenthesis or nothing. Valid values range from 0 to BOOST_PP_LIMIT_MAG.

#### Remarks

If cond expands to 0, this macro expands to nothing. Otherwise, it expands to a left parenthesis.
The preprocessor interprets parentheses as delimiters in macro invocations. Because of this, parentheses require special handling.

#### See Also

- BOOST_PP_LIMIT_MAG
- BOOST_PP_RPAREN_IF

#### Requirements

Header: <boost/preprocessor/punctuation/paren_if.hpp>

#### Sample Code

    #include <boost/preprocessor/punctuation/paren_if.hpp>

    #define MACRO(c, x) BOOST_PP_LPAREN_IF(c) x BOOST_PP_RPAREN_IF(c)

    MACRO(0, text) // expands to text
    MACRO(1, text) // expands to (text)