Is Omitting the Leading Colon in PDOStatement::bindParam() Named Parameters a Supported Behavior?

Omission of Leading Colon with Named Parameters in PDOStatement::bindParam()

In PDOStatement::bindParam(), it appears that passing named parameters without a leading colon (e.g., ':name') works equivalently to including the colon (e.g., 'name'). This behavior may seem puzzling given the documentation, which states that the "parameter identifier" should include the leading colon for named placeholders.

Official Support

The PDOStatement::bindParam() documentation does not explicitly state that the leading colon is optional for named parameters. Therefore, it is prudent to assume that this behavior is not officially supported and should not be used in production code.

Underlying Mechanism

Despite the lack of official documentation, the omission of the leading colon does appear to function in PHP versions such as 5.3.24 due to an internal mechanism. Specifically, if a colon is missing, it is automatically added to the parameter during the execution of PDOStatement::bindParam(). This internal fix can be observed in the PDO source code (ext/pdo/pdo_stmt.c).

Recommendation

While it may be possible to omit the leading colon in named parameters in the current PHP version, it is not recommended. The absence of official support means that future PHP versions may not maintain this behavior, leading to potential errors. Consequently, it is always best practice to consistently include the leading colon when passing named parameters to PDOStatement::bindParam() for maximum compatibility and reliability.

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