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Add RUNNABLE_EXAMPLES macros to in-text examples in std.exception

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Sebastian Wilzbach 2018-01-28 19:14:02 +01:00
parent afa7d586dd
commit cbecad703e
1 changed files with 17 additions and 0 deletions
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17
std/exception.d
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@ -823,6 +823,7 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
*
* Example:
*
* $(RUNNABLE_EXAMPLE
* ----
* string letters()
* {
@ -834,6 +835,7 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
* return assumeUnique(result);
* }
* ----
* )
*
* The use in the example above is correct because $(D result)
* was private to $(D letters) and is inaccessible in writing
@ -842,6 +844,7 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
*
* Bad:
*
* $(RUNNABLE_EXAMPLE
* ----
* private char[] buffer;
* string letters(char first, char last)
@ -856,11 +859,13 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
* return assumeUnique(sneaky); // BAD
* }
* ----
* )
*
* The example above wreaks havoc on client code because it is
* modifying arrays that callers considered immutable. To obtain an
* immutable array from the writable array $(D buffer), replace
* the last line with:
*
* ----
* return to!(string)(sneaky); // not that sneaky anymore
* ----
@ -872,6 +877,8 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
* marked as a pure function. The following example does not
* need to call assumeUnique because the compiler can infer the
* uniqueness of the array in the pure function:
*
* $(RUNNABLE_EXAMPLE
* ----
* string letters() pure
* {
@ -883,6 +890,7 @@ enum emptyExceptionMsg = "<Empty Exception Message>";
* return result;
* }
* ----
* )
*
* For more on infering uniqueness see the $(B unique) and
* $(B lent) keywords in the
@ -1557,15 +1565,18 @@ class ErrnoException : Exception
errorHandler.
Example:
$(RUNNABLE_EXAMPLE
--------------------
//Revert to a default value upon an error:
assert("x".to!int().ifThrown(0) == 0);
--------------------
)
You can also chain multiple calls to ifThrown, each capturing errors from the
entire preceding expression.
Example:
$(RUNNABLE_EXAMPLE
--------------------
//Chaining multiple calls to ifThrown to attempt multiple things in a row:
string s="true";
@ -1580,12 +1591,14 @@ class ErrnoException : Exception
.ifThrown!Exception("number too small")
== "not a number");
--------------------
)
The expression and the errorHandler must have a common type they can both
be implicitly casted to, and that type will be the type of the compound
expression.
Example:
$(RUNNABLE_EXAMPLE
--------------------
//null and new Object have a common type(Object).
static assert(is(typeof(null.ifThrown(new Object())) == Object));
@ -1595,13 +1608,17 @@ class ErrnoException : Exception
static assert(!__traits(compiles, 1.ifThrown(new Object())));
static assert(!__traits(compiles, (new Object()).ifThrown(1)));
--------------------
)
If you need to use the actual thrown exception, you can use a delegate.
Example:
$(RUNNABLE_EXAMPLE
--------------------
//Use a lambda to get the thrown object.
assert("%s".format().ifThrown!Exception(e => e.classinfo.name) == "std.format.FormatException");
--------------------
)
+/
//lazy version
CommonType!(T1, T2) ifThrown(E : Throwable = Exception, T1, T2)(lazy scope T1 expression, lazy scope T2 errorHandler)