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### 73. `is_open` should be const

Section: 31.10 [file.streams] Status: NAD Submitter: Matt Austern Opened: 1998-08-27 Last modified: 2017-06-15

Priority: Not Prioritized

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Discussion:

Classes `basic_ifstream`, `basic_ofstream`, and `basic_fstream` all have a member function `is_open`. It should be a `const` member function, since it does nothing but call one of `basic_filebuf`'s const member functions.

Rationale:

Not a defect. This is a deliberate feature; const streams would be meaningless.