Exception handler

Exception handler is defined as a set of processes to be executed when some errors are detected while executing certain set of processes. These error-handling processes are written useing try catch . The syntax is probably obvious from the next example:

    try{
        for(x = 0, 1, 0.01){
            y = f(x) / g(x)
            print y
        }
    }catch(g(x) = 0){
        print 'Divided by 0!'
    }

The result is the following:

The output PAD figure is as same as if statement. This is because there is no such concept as exception handler in PAD itself.

The rules for putting a return code and { } is as same as that of repetition and conditional branch. If the content of try or catch is in one line, you do not have to enclose the content with { }. You can add a return code before and after { or }, and you can put as many spaces as you like. Hence, the next example is valid.

    try
        print sty
    catch(str = NULL)
        print 'NULL!'
    
    try
    {
        print sty
    }
    catch (str = NULL) {
        print 'NULL!'
    }

The next example is invalid.

    try{  print sty  }
    catch(str = NULL)  print 'NULL!'

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Sun Nov 10 01:36:04 JST 1996