On 9/27/2014 4:59 PM, bearophile wrote:
Walter Bright:
Even if that is what you wanted, you won't get that from FileException, as it
will only show file/lines emanating from calls inside std.file, not from
higher level callers.
Can't we use the template arguments like __LINE__ to offer the line of code in
the IO function in user code?
We could, but again, WHOA CAMEL!
Also, one should be careful in using __LINE__ in a template, as it will be
forced to generate a new instantiation with every use.
Besides, take a bit of care when formulating a string for exceptions, and you
won't have any trouble grepping for it. This isn't rocket science.
The exception is generated inside library code, not in user code. There's
nothing to grep in the user code. The D script often looks like this:
void main() {
import std.stdio;
auto file_name = "some_file;
// some code here
auto file_name1 = file_name ~ "1.txt";
auto f1 = File(file_name1);
// some code here
auto file_name2 = file_name ~ "2.txt";
auto f2 = File(file_name2, "w");
// some code here
}
Come on. What is hard about "Cannot open file `xxxx` in mode `xxxx`", then you
grep for "Cannot open file" ?
Let's try it:
> grep "Cannot open file" *.d
stdio.d: text("Cannot open file `", name, "' in mode `",
stdio.d:// new StdioException("Cannot open file `"~fName~"' for reading"));
stdio.d:// new StdioException("Cannot open file `"~fName~"' for reading"));
Besides, File doesn't throw a FileException and doesn't add caller's __FILE__
and __LINE__.
If you're seriously proposing adding __FILE__ and __LINE__ to every function
call, then D is the wrong language. This would have disastrous bloat and
performance problems. You mentioned Python and Ruby, both of which are well
known for miserable performance.
Building the equivalent of a symbolic debugger into RELEASED D code is just not
acceptable.
Presenting internal debugging data to users for input/environmental errors is
just bad programming practice.7 We shouldn't be enshrining it in Phobos and
presenting it as a professional way to code.
The file/line of code is not meant to replace serious practices for dealing with
I/O failures in serious D programs.
That's exactly what you're doing with it.
