TIP #178 Version 1.3: [info pid] and [info tid] Subcommands

This is not necessarily the current version of this TIP.

Abstract

This TIP proposes two new [info] subcommands which are used to obtain the current process and thread identifiers.

Rationale

In certain types of applications, it is important to know what thread is currently executing. This is especially true for multithreaded applications or for scripts running in a threaded build of Tcl.

While the author realizes that there is already a [pid] command, the addition of the [info pid] subcommand still makes sense for the following reasons:

• The [pid] command can also provide information totally unrelated to the current process identifier. At one point (TIP #88) it was even suggested that the [pid] command be overloaded to provide process control related functionality.

• To allow scripts that dynamically build other scripts (potentially for use with safe interpreters) using the [info] command and caller provided arguments. Using the [info] command instead of the [pid] command limits the amount of information that can be obtained by the safe interpreter.

• It is the opinion of the author that informational commands, such as [pid] should really be subcommands of [info] as we start to move forward with the development of Tcl.

Proposed Change

Two new subcommands, [info pid] and [info tid], would be added to the [info] command with the following syntax:

info pid

This subcommand would return the process identifier for the current process.

info tid

This subcommand would return the thread identifier for the current thread.

Draft Implmentation

A complete implementation of this TIP is availble at:

http://sf.net/tracker/?func=detail&aid=920731&group_id=10894&atid=310894

Copyright

This document has been placed in the public domain.

This is not necessarily the current version of this TIP.