Invert if/else/error
Introduction
The C++ error handling mechanism in core Octave has been changed to use exceptions. Previously, calling error() in C++ would always return execution to the calling function. This made it necessary to explicitly use the else keyword to control program flow. With exceptions, the C++ code may now be written in a manner that closely resembles Octave's own m-file language.
The principal work for this topic is to convert if/else statements that have an error() call in the else branch to a new format. The goal is to move the error() call to be after the if statement, eliminate the else branch, and decrease the indent of the remaining code. This requires reversing the conditional test in the if. For a single condition, the condition should be reversed rather than just adding the negation operator '!' to the start of the conditional. For a test with multiple conditions, use DeMorgan's Law (Demorgan's Law). In brief, you will need to negate each individual conditional and then change all && to || or vice versa.
Example 1 : Single Conditional (rows() from data.cc)
| Before | After |
|---|---|
bool do_set (const octave_value& v)
{
if (v.is_scalar_type () && v.is_real_type ())
{
double new_val = v.double_value ();
if (new_val != current_val)
{
current_val = new_val;
return true;
}
}
else
error ("set: invalid value for double property \"%s\"",
get_name ().c_str ());
return false;
}
|
bool do_set (const octave_value& v)
{
if (! v.is_scalar_type () || ! v.is_real_type ())
error ("set: invalid value for double property \"%s\"",
get_name ().c_str ());
double new_val = v.double_value ();
if (new_val != current_val)
{
current_val = new_val;
return true;
}
return false;
}
|
Detailed Instructions
The list of files which contain an instance of else followed by error() is shown in the Files section of this page. The actual instances, including line numbers, are shown in the Instances section. To avoid duplication, sign up for a particular file by editing the Files section of this wiki page and replacing '???' with your name. When you have edited a file you should verify that everything is okay by executing
make all ./run-octave test FILENAME
When that passes, upload your patch to the patch tracker https://savannah.gnu.org/patch/?group=octave. If you can, e-mail the Octave Maintainer's list at octave-maintainers@gnu.org and let us know that there is something to review. Also, add the wiki tags
<strike> ... </strike>
to the Files section to cross the file off the list. In addition, increment the number of files that were fixed by +1.
Files
Total: 43
Fixed: 5
| Owner | File |
|---|---|
| ??? | corefcn/Cell.cc |
| ??? | corefcn/__ilu__.cc |
| ??? | corefcn/bitfcns.cc |
| ??? | corefcn/cellfun.cc |
| ??? | corefcn/data.cc |
| ??? | corefcn/debug.cc |
| ??? | corefcn/error.cc |
| jwe | |
| jwe | |
| ??? | corefcn/input.cc |
| ??? | corefcn/load-save.cc |
| ??? | corefcn/ls-mat-ascii.cc |
| ??? | corefcn/ls-mat5.cc |
| ??? | corefcn/ls-oct-text.cc |
| ??? | corefcn/oct-map.cc |
| ??? | corefcn/oct-stream.cc |
| ??? | corefcn/sparse-xpow.cc |
| ??? | corefcn/symtab.h |
| ??? | corefcn/typecast.cc |
| ??? | corefcn/urlwrite.cc |
| das | |
| das | corefcn/variables.cc |
| jwe | dldfcn/chol.cc |
| ??? | octave-value/ov-base-diag.cc |
| ??? | octave-value/ov-base-int.cc |
| ??? | octave-value/ov-base-mat.cc |
| ??? | octave-value/ov-base-sparse.cc |
| ??? | octave-value/ov-base.cc |
| ??? | octave-value/ov-bool-mat.cc |
| ??? | octave-value/ov-cell.cc |
| ??? | octave-value/ov-class.cc |
| ??? | octave-value/ov-classdef.cc |
| ??? | octave-value/ov-cx-mat.cc |
| ??? | octave-value/ov-flt-cx-mat.cc |
| ??? | octave-value/ov-flt-re-mat.cc |
| ??? | octave-value/ov-perm.cc |
| ??? | octave-value/ov-re-mat.cc |
| ??? | octave-value/ov-str-mat.cc |
| ??? | octave-value/ov-struct.cc |
| ??? | octave-value/ov-usr-fcn.cc |
| ??? | octave-value/ov.cc |
| jwe | |
| jwe |
Instances
Total: 104
Fixed: 0
corefcn/graphics.in.h:1194 corefcn/symtab.h:151 corefcn/Cell.cc:306 corefcn/__ilu__.cc:767 corefcn/bitfcns.cc:111 corefcn/bitfcns.cc:506 corefcn/bitfcns.cc:509 corefcn/cellfun.cc:219 corefcn/cellfun.cc:686 corefcn/data.cc:658 corefcn/data.cc:838 corefcn/data.cc:1381 corefcn/data.cc:5620 corefcn/debug.cc:1383 corefcn/error.cc:1863 corefcn/graphics.cc:1313 corefcn/graphics.cc:1332 corefcn/graphics.cc:1365 corefcn/graphics.cc:1570 corefcn/graphics.cc:2514 corefcn/graphics.cc:2517 corefcn/graphics.cc:2540 corefcn/graphics.cc:10132 corefcn/graphics.cc:10634 corefcn/graphics.cc:10641 corefcn/graphics.cc:11454 corefcn/input.cc:761 corefcn/load-save.cc:748 corefcn/ls-mat-ascii.cc:322 corefcn/ls-mat-ascii.cc:343 corefcn/ls-mat-ascii.cc:347 corefcn/ls-mat-ascii.cc:351 corefcn/ls-mat5.cc:596 corefcn/ls-mat5.cc:1023 corefcn/ls-mat5.cc:2329 corefcn/ls-oct-text.cc:285 corefcn/oct-map.cc:277 corefcn/oct-stream.cc:1843 corefcn/sparse-xpow.cc:125 corefcn/sparse-xpow.cc:198 corefcn/typecast.cc:84 corefcn/typecast.cc:294 corefcn/urlwrite.cc:276 corefcn/utils.cc:1158 corefcn/utils.cc:1187 corefcn/variables.cc:174 corefcn/variables.cc:1499 dldfcn/chol.cc:216 dldfcn/chol.cc:241 octave-value/ov-base-diag.cc:528 octave-value/ov-base-int.cc:231 octave-value/ov-base-mat.cc:96 octave-value/ov-base-sparse.cc:464 octave-value/ov-base.cc:1614 octave-value/ov-base.cc:1632 octave-value/ov-bool-mat.cc:265 octave-value/ov-bool-mat.cc:294 octave-value/ov-cell.cc:809 octave-value/ov-cell.cc:818 octave-value/ov-cell.cc:848 octave-value/ov-cell.cc:863 octave-value/ov-cell.cc:963 octave-value/ov-class.cc:1272 octave-value/ov-class.cc:1275 octave-value/ov-class.cc:1707 octave-value/ov-class.cc:1710 octave-value/ov-classdef.cc:530 octave-value/ov-classdef.cc:558 octave-value/ov-classdef.cc:588 octave-value/ov-classdef.cc:1758 octave-value/ov-classdef.cc:2054 octave-value/ov-classdef.cc:2403 octave-value/ov-classdef.cc:2572 octave-value/ov-classdef.cc:3144 octave-value/ov-classdef.cc:3183 octave-value/ov-classdef.cc:3248 octave-value/ov-classdef.cc:3443 octave-value/ov-cx-mat.cc:324 octave-value/ov-cx-mat.cc:398 octave-value/ov-cx-mat.cc:422 octave-value/ov-flt-cx-mat.cc:298 octave-value/ov-flt-cx-mat.cc:372 octave-value/ov-flt-cx-mat.cc:396 octave-value/ov-flt-re-mat.cc:276 octave-value/ov-flt-re-mat.cc:399 octave-value/ov-flt-re-mat.cc:423 octave-value/ov-perm.cc:308 octave-value/ov-re-mat.cc:285 octave-value/ov-re-mat.cc:501 octave-value/ov-re-mat.cc:525 octave-value/ov-str-mat.cc:233 octave-value/ov-str-mat.cc:250 octave-value/ov-str-mat.cc:269 octave-value/ov-str-mat.cc:382 octave-value/ov-str-mat.cc:419 octave-value/ov-str-mat.cc:426 octave-value/ov-struct.cc:764 octave-value/ov-struct.cc:1403 octave-value/ov-usr-fcn.cc:158 octave-value/ov-usr-fcn.cc:162 octave-value/ov-usr-fcn.cc:989 octave-value/ov.cc:2995 parse-tree/pt-assign.cc:278 parse-tree/pt-idx.cc:524