MicroStation and Application Development

MicroStation^® is a computer-aided-design (CAD) tool produced by Bentley Systems. It is used by engineers, architects, and draughting technicians to create 3D models and 2D drawings.

MicroStation can be customised. Bentley Systems themselves have many applications for specialised markets that use MicroStation as a platform. Third-parties likewise may use MicroStation as a platform on which to develop their application software. Bentley Systems provide the MicroStation Software Development Kit (SDK) that software developers use to create their applications.

The SDK has two libraries: the MicroStation Development Library (MDL) and the MicroStationAPI. The MicroStation Development Library contains thousands of functions that provide a C-language interface. The MicroStationAPI provides an object-oriented C++ interface.

StringLib: a String Library

StringLib provides some String Library free functions and a CfgVar class to help with configuration variables. Some of the string functions are general-purpose: for example, there's a string splitter, useful for dealing with multi-path configuration variables. The CfgVar class wraps some of the mdlSystem_api functions that deal with configuration variables.

C++ Standard Library

The String Library uses the C++ Standard Library, including std::string and std::vector.

C++ Namespace

The String Library lives inside the LASolutions namespace. The free functions live in the StringLib nested namespace.

typedefs

If you're not familiar with the Standard Library or templates, the typedef syntax may appear as if a cat walked over the keyboard. We want to have an elastic array of values; the Standard Library calls an elastic array a <vector>. We declare a vector of strings like this …

std::vector<std::string> elasticArrayOfStrings;

However, typing all those chevrons become tedious, so we create an alias, known in C as a typedef. Here's the alias for our elastic array of strings …

typedef std::vector<std::string> StringCollection;

Having created that alias, our variable declaration is a lot clearer …

StringCollection elasticArrayOfStrings;

CfgVar class

Here's the public interface for the CfgVar class. I've removed the namespace to simplify what you see here …

bool                Valid               () const;
void                SetCfgVar           (char const* cfgvar);
std::string const&  GetCfgVar           () const;
std::string         Definition          () const;
std::string         Expand              () const;
bool                IsMultipath         () const;
int                 Paths               (LASolutions::StringCollection& paths) const;
CfgVar (char const* cfgvar);

CfgVar Simple Example

Instantiate the CfgVar class with the name of a configuration variable. Then use its methods to see the definition or expanded value of that variable. For example …

#include <StringLibImpl.h>

CfgVar cfgVar ("MS_DEF");
if (cfgVar.Valid ())
{
    std::string definition = cfgVar.Definition ();  // e.g. $(PROJECTS)project1/dgn/ 
    std::string expanded = cfgVar.Expand ();        // e.g. C:/projects/project1/dgn/ 
}

CfgVar Multipath Example

Instantiate the CfgVar class with the name of a configuration variable. Then use its methods to see the definition or expanded value of that variable. Often, configuration variable MS_DEF or MS_RFDIR is a multipath variable: that is, it contains a list of folders separated (usually) by a semi-colon. For example …

#include <StringLibImpl.h>

CfgVar cfgVar ("MS_DEF");
if (cfgVar.Valid ())
{
    std::string definition = cfgVar.Definition ();  // e.g. $(PROJECTS)project1/dgn/;$(COMMON)borders/;$(SHARED_PROJECT_DATA)components/ 
    std::string expanded = cfgVar.Expand ();        // e.g. C:/projects/project1/dgn/;V:/group/cad/borders/;V:/construction/detail/components/ 

    StringCollection paths;
    if (cfgVar.Paths (paths))
    {
        //  Iterate paths in StringCollection
        //  e.g. C:/projects/project1/dgn/
        //       V:/group/cad/borders/
        //       V:/construction/detail/components/
    }
}

Example StringLib Project

We've created a sample project that exercises StringLib. It provides examples of the free function usage as well as CfgVar class usage. The StringLib project provides two MicroStation keyin commands …

• STRINGLIB CFGVAR EXPAND CLASS <variable-name>: illustrates the CfgVar class
• STRINGLIB CFGVAR EXPAND PROCEDURAL <variable-name>: illustrates the free functions

Download the StringLib Project

Download the StringLib project. This ZIP file contains C++ source code header and implementation files, and a bmake (.mke) file to build the project. You need Visual Studio 2005 to be installed in order to compile this project.