CODEWITHSUNDEEP
c++qt
Tim Hoffmann
Tim Hoffmann

Reputation: 1345

Test for default-constructed QFileInfo

I want to use an optional argument of type QFileInfo. What is the canonical way to test if the caller provided a value or if the default was used?

// declaration
void foo(QFileInfo fi = QFileInfo());

// definition
void foo(QFileInfo fi)
{
    if ( /* what to test for: "is default" */ ) {

    }
}

Usually default-constructed Qt objects have something like isValid() or isEmpty(). However, there seems no such thing in QFileInfo.

One option would be fi.filePath().isEmpty(). Is there something better / simpler?

Upvotes: 5

Views: 446

Answers (2)

Matteo Italia
Matteo Italia

Reputation: 126807

The fi.filePath().isEmpty() seems to be the most straightforward and efficient, given that the effect of calling the default constructor is to create a QFileInfo with no file reference.

QFileInfo::QFileInfo()

Constructs an empty QFileInfo object.

Note that an empty QFileInfo object contain no file reference.

Upvotes: 3

TheWaterProgrammer
TheWaterProgrammer

Reputation: 8239

Additionally you can check if the file exists after you receive the QFileInfo in your function

void foo(QFileInfo fi)
{
  if ( fi.exists() && fi.isFile() ) {
    // execute your logic
  }
}

Upvotes: 0

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