IRT Command Language (ICL)

This page contains a description of the source code for IRT Command Language (ICL), describes how to obtain the ICL source code, and provides information needed in order to compile ICL.

Development of ICL is managed through the SourceForge website as part of the Social Science Measurement project. Participation in the development of ICL is encouraged. Two Social Science Measurement project mailing lists are used to communicate information about ICL. The ssm-announce mailing list is used to make announcements about new releases of Social Science Measurement projects, including ICL. The ssm-devel mailing list is for discussion of ICL development, and the development of other Social Science Measurement projects. Anyone is welcome to subscribe to either mailing list. The source code comprising ICL can be downloaded from the SourceForge website, or from the link below. The latest development versions of the ICL source files can be obtained from the Social Science Measurement CVS repository at the SourceForge website.

Download ICL source code - Zip archive containing ICL source files. The source files in this archive are stored with DOS line breaks (the files are DOS text files).

ICL is written in C++, so a C++ compiler is needed to compile ICL. Version 2.95.2 of the GCC compiler was used to compile ICL under Linux, and version 7.2 of the Metrowerks CodeWarrior compiler was used to compile ICL under Mac OS. The Windows version of ICL was compiled using MinGW, which allows Windows programs to be compiled using GCC 2.95.2. The Windows version of ICL was cross-compiled under Linux using a version of MinGW running on Linux. ICL should compile using other C++ compilers that have a similar level of compliance with the C++ standard (e.g., the free Borland 5.5 compiler for Windows). Some modifications may be needed to compile ICL using Microsoft Visual C++ version 6. The symbol ETIRM_USE_BOOST_CONFIG should be defined when trying to compile ICL using Microsoft Visual C++ so the Boost configure system can define the appropriate symbols (see below for information about the Boost C++ libraries).

Several tools described below were used in compiling ICL. These need to be separately downloaded. It is not necessary to have all these tools to compile the ICL source code since the source files produced by some of the tools (SWIG and mktclapp) are distributed as part of the ICL source code distribution. It may be necessary to use all these tools if changes are made to the ICL source code.

• Estimation Toolkit for Item Response Models (ETIRM) - ETIRM provides the numerical routines used by ICL. The current version of ICL was compiled using ETIRM version 0.020228.

• Tcl Libraries - The Tcl source code is needed to create static Tcl libraries which are linked into ICL. The Tcl libraries need be compiled following the instructions in the Tcl source code distribution. Version 8.3.2 of Tcl was used for the Windows and Linux versions of ICL. For the Macintosh version of ICL the Macintosh source code for version 8.3.4 of Tcl was used.

• Mktclapp - Used to create the stand alone ICL applications for Windows and Linux, which contain an embedded copy of the source code for ICL commands that are written in Tcl (from the source file icl.tcl). Mktclapp is used to produce the source files icl_win.cpp and icl_linux.cpp. The current version of ICL was created using mktclapp version 3.11.

• Simplified Wrapper and Interface Generator (SWIG) - Used to create Tcl wrappers for the C++ source code. Note that SWIG can generate wrappers for other scripting languages such as Perl and Python. Creating a version of ICL based on a scripting language supported by SWIG other than Tcl is possible using the existing code along with a SWIG input file for that language analogous to the Tcl version (icl.swg). SWIG is used to produce the source file icl_wrap.cpp. The current version of ICL was created using SWIG version 1.3.11.

• STLport - An implementation of the C++ standard library used to compile the Windows and Linux versions of ICL. STLport is needed when compiling ICL using gcc 2.95.2 due to limitations in the C++ standard library implementation. STLport may not be needed when compiling ICL using other C++ compilers, or later versions of gcc. The current version of ICL was created using STLport version 4.5.1.

• Boost C++ Libraries - ICL uses random number classes from the Boost libraries in the functions for boot straping and simulating item responses. The current version of ICL was created using version 1.27.0 of the Boost libraries.

The top level of the source code distribution contains files needed to compile the Linux and Windows versions of ICL. Descriptions of these files are given below.

• appinit.cpp - Contains Et_AppInit function that initializes commands created by SWIG within the program created by mktclapp.
• icl_linux.cpp - Main program for Linux application generated my mktclapp containing wrapped Tcl source code.
• icl_win.cpp - Main program for Windows application generated my mktclapp containing wrapped Tcl source code.
• icl.swg - SWIG input file to generate Tcl wrapper file icl_wrap.cpp that includes functions declared in swig_etirm.h (part of ETIRM) and swig_icl.h.
• icl_linux.mta - Input file to mktclapp used to generate icl_linux.cpp for the Linux application. Directory paths in this file will need to be changed or the file recreated using the Tk interface to mktclapp (xmktclapp.tcl).
• icl_win.mta - Input file to mktclapp used to generate icl_win.cpp for the Windows application. Directory paths in this file will need to be changed or the file recreated using the Tk interface to mktclapp (xmktclapp.tcl).
• icl.tcl - Source code for ICL commands written in Tcl.
• icl_wrap.cpp - Source code for ICL commands written in C++ wrapped by SWIG to be compiled into a Tcl interpreter. This file is generated by SWIG from icl.swg.
• Makefile - Contains the sequence of steps needed to create the Linux ICL executable.
• Makefile.win - Contains the sequence of steps needed to create the Windows ICL executable.
• swig_icl.cpp and swig_icl.h - Functions and classes for ICL commands written in C++. The file swig_icl.h and the ETIRM file swig_icl.h are used with SWIG to generate Tcl language wrappers for the ICL functions written in C++.
• swig_etirm_types.h - Definition of types that are referenced in the ETIRM file swig_etirm.h.

The mac directory contains files that are needed, in addition to some of those described above, to compile the Macintosh version of ICL. Descriptions of these files are given below.

• icl.mcp.xml - Exported Metrowerks Codewarrior version 7.2 project file for the Macintosh version of ICL. This file can be used to import the project using the Import File menu item under the File menu in Metrowerks CodeWarrior 7.2.
• icl.rsrc.hqx - Resources needed for the Macintosh application encoded in BinHex format. This file needs to be decoded using StuffIt Expander.
• icl_tcl.r - Copies the Tcl source code needed for the Macintosh application into resources to create a stand alone application.
• ICLMacAppInit.c - Contains main function for Macintosh version of ICL.
• icl_prefix.h - Prefix file used for the Metrowerks project.

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Last updated: March 1, 2002