MCurrentPathSubstitutor Class Reference

Locally substitute the current path of an application to another current path. More...

Public Member Functions
	MCurrentPathSubstitutor (const MStdString &newPath)
	Construct current path substitutor object, supply a new directory name, or a file name located in the required path. More...
	~MCurrentPathSubstitutor ()
	Destroy the object, and restore the old default path which existed at the time of creation of the object.
const MStdString &	GetSavedCurrentPath () const
	Get the old application path which existed before the constructor of this class has attempted to set a new path.
const MStdString &	GetNewCurrentPath () const
	Get the new application path, which was attempted to be set in the constructor of this class. More...

Detailed Description

Locally substitute the current path of an application to another current path.

The previous current path is restored in the destructor of the class. Worth noting that this call shall be used with caution in a multithreaded environment, as it replaces process current path. Therefore, if some other thread makes the same call, or expects the current path to stay unchanged, the behavior will be undefined.

This class would be used in a function that needs to temporarily set a different current path, and might throw an exception. The algorithms of this class ensure that the current application path will be restored whether or not an exception is thrown, or a function ended peacefully. To make this class work, one needs to declare a local variable of this class as a automatic stack-based variable, like:

void MyFuncThatNeedsToSubstitutePath()
{
    MCurrentPathSubstitutor substitutePath("c:\\new\\temporary\\path");
    .... // this is where the path will be new
} // after the function returns in whatever way, the old path will be restored 

Static service GetCurrentPath of MUtilities can be used at any time to get the current path.

Note there is a popular C++ logic error not to mention the variable after the class. Like in the example above, one could omit substitutePath without the compiler complaining. However in this case the path will be substituted per only one line of code (up the semicolon), which is not an intent of this class. Also, one shall not attempt to copy or compare this class. Provisions through private services are made.

Constructor & Destructor Documentation

MCurrentPathSubstitutor::MCurrentPathSubstitutor

(

const MStdString &

newPath

)

Construct current path substitutor object, supply a new directory name, or a file name located in the required path.

In case of failure, this constructor will not throw an exception, but property GetNewCurrentPath will be empty if path could not be changed.

Parameters

newPath

The new current directory name. The directory should exist, and have appropriate permissions for the current user, or the behavior is undefined, otherwise the path will not be changed.

Member Function Documentation

const MStdString& MCurrentPathSubstitutor::GetNewCurrentPath ( ) const

inline

Get the new application path, which was attempted to be set in the constructor of this class.

• If the path was replaced, this is the same as the file or directory given.
• If the path was not set for any reason, this will be an empty string.