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digitalmars.D.learn - formattedWrite writes nothing

reply "ref2401" <refactor24 gmail.com> writes:
class MyClass {
	Appender!string _stringBuilder;

	this() {
		_stringBuilder = Appender!string(null);
		_stringBuilder.clear();
	}

	 property string str() {
		return _stringBuilder.data;
	}

	void append(string s) {
		formattedWrite(_stringBuilder, "%s", s);
	}
}

MyClass c = new MyClass();
c.append("text 1");
c.append("__222");

writeln(c.str); //in this case nothing is printed out

Following workarounds work:
1) call _stringBuilder.put() instead of formattedWrite()
2) if "_stringBuilder.clear()" is omitted in the constructor, 
formattedWrite(...) will work as expected.

Is it a bug or is there a reason for such behaviour?
May 02 2014
next sibling parent reply Andrej Mitrovic via Digitalmars-d-learn writes:
On 5/2/14, ref2401 via Digitalmars-d-learn
<digitalmars-d-learn puremagic.com> wrote:

 class MyClass {
 	Appender!string _stringBuilder;

 	this() {
 		_stringBuilder = Appender!string(null);
 		_stringBuilder.clear();


Ouch, ouch, ouch! What's happening is that the 'clear' Appender method
is only compiled-in if the data is mutable, otherwise you end up
calling the object.clear UFCS function. So don't use clear here.

I don't know if this is a case of poor method naming or another
downside of UFCS. Luckily 'clear' is being renamed to 'destroy' in the
object module, so this specific case will not become a problem in the
future.
May 02 2014
parent "anonymous" <anonymous example.com> writes:
On Friday, 2 May 2014 at 10:23:03 UTC, Andrej Mitrovic via 
Digitalmars-d-learn wrote:

 Ouch, ouch, ouch! What's happening is that the 'clear' Appender 
 method
 is only compiled-in if the data is mutable, otherwise you end up
 calling the object.clear UFCS function. So don't use clear here.

 I don't know if this is a case of poor method naming or another
 downside of UFCS. Luckily 'clear' is being renamed to 'destroy' 
 in the
 object module, so this specific case will not become a problem 
 in the
 future.


I'd say clear should be  disabled in Appender for non-mutable 
data.
May 02 2014
prev sibling parent "Jared Miller" <jared economicmodeling.com> writes:
I logged this bug a while ago:

https://issues.dlang.org/show_bug.cgi?id=10291


On Friday, 2 May 2014 at 10:06:43 UTC, ref2401 wrote:

 Is it a bug or is there a reason for such behaviour?
May 02 2014