Feature request: Custom ProgressBar/ProgressCounter message

[tylermorganwall]

Fiirst off, great package--really enjoy using it.

Right now, the ProgressBar/ProgressCounter classes have the message "Computing: " hard coded in before the progress bar.

class ProgressCounter : public ProgressPrinter {

public:
    //! constructs a progress counter.
    //! @param numIt total number of iterations.
    //! @param printEvery how regularly to print updates (in seconds).
    ProgressCounter(size_t numIt, size_t printEvery) :
        ProgressPrinter(numIt, printEvery)
    {}

private:
    //! prints progress in percent to the R console (+ an estimate of remaining
    //! time).
    void printProgress() {
        if (isDone_)
            return;
        if (it_ == numIt_)
            isDone_ = true;
        std::ostringstream msg;
        msg << "\rComputing: " << progressString();
        Rcout << msg.str();
    }
};

It would be nice to be able to pass a custom string to use in place of that message as part of the constructor, e.g.

class ProgressCounter : public ProgressPrinter {

public:
    //! constructs a progress counter.
    //! @param numIt total number of iterations.
    //! @param printEvery how regularly to print updates (in seconds).
    ProgressCounter(size_t numIt, size_t printEvery, std::string custom_msg = "Computing: ") :
        ProgressPrinter(numIt, printEvery), cmsg(custom_msg)
    {}

private:
    std::string cmsg;
    //! prints progress in percent to the R console (+ an estimate of remaining
    //! time).
    void printProgress() {
        if (isDone_)
            return;
        if (it_ == numIt_)
            isDone_ = true;
        std::ostringstream msg;
        msg << "\r" << cmsg << progressString();
        Rcout << msg.str();
    }
};

The use case is when you have multiple steps of computation with different progress bars, it's nice for the progress bar to show what stage the user is currently in.

[tnagler]

That's a great idea, thanks for the suggestion! I'll try to get to it next week (the coding part should be easy, but reverse dependency testing + CRAN release usually takes a few hours).