Mercurial > octave
changeset 23134:01bf5c733de7 stable
doc: Expand documentation for cast() (bug #50201).
* cast.m: Clarify behavior of cast and add a programming note explaining how it
might be used with user-defined classes.
| author | Rik <rik@octave.org> |
|---|---|
| date | Wed, 01 Feb 2017 21:06:04 -0800 |
| parents | 0f2582425a9e |
| children | be2654b2f34f 4e313457b5f9 |
| files | scripts/miscellaneous/cast.m |
| diffstat | 1 files changed, 14 insertions(+), 1 deletions(-) [+] |
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--- a/scripts/miscellaneous/cast.m Wed Feb 01 20:39:51 2017 -0800 +++ b/scripts/miscellaneous/cast.m Wed Feb 01 21:06:04 2017 -0800 @@ -20,7 +20,8 @@ ## @deftypefn {} {} cast (@var{val}, "@var{type}") ## Convert @var{val} to data type @var{type}. ## -## @var{val} must be one of the numeric classes: +## Both @var{val} and @var{type} are typically one of the following built-in +## classes: ## ## @example ## @group @@ -52,6 +53,18 @@ ## @end group ## @end example ## +## Programming Note: This function relies on the object @var{val} having a +## conversion method named @var{type}. User-defined classes may implement only +## a subset of the full list of types shown above. In that case, it may be +## necessary to call cast twice in order to reach the desired type. +## For example, the conversion to double is nearly always implemented, but +## the conversion to uint8 might not be. In that case, the following code will +## work +## +## @example +## cast (cast (@var{user_defined_val}, "double"), "uint8") +## @end example +## ## @seealso{typecast, int8, uint8, int16, uint16, int32, uint32, int64, uint64, double, single, logical, char, class, typeinfo} ## @end deftypefn