T < x < B

Function/constructor duality

Fri, 08 Oct 2010 02:59:00 -0400

Waldo: what's the canonical way of detecting whether you're being called from a constructor?
um

s/from a/as a
cdleary-lappy: what's regexp_call do?
(it calls a common helper as I recall)

I meant in JS itself -- is there an idiom for that?
you can't
you can sometimes know you *weren't* called that way
but even then not always

what's the "not always" case?

(probably a discussion for #jslang, but w/e)
function C() { if (!(this instanceof C)) throw "not new"; }; var c = new C; C.call(c);

ah, tricky
function C() { if (!(this instanceof C) || this.constructed) throw "not new"; Object.defineProperty(this, "constructed", { value: true }); }; var c = new C; C.call(c) /* *will* throw */;
that's the only hackaround I know

Waldo: seems like reasonable usage will work with the simple instanceof test, though
yes

constructing an invoking separately was something I wasn't even aware of! :-)
it takes some work to get this in one's head

what's annoying about it, though, is that you need the constructor binding hack to get arguments in the constructor after the check

eh, I guess not, you can just make the two forms expect different arguments form, but it's still quite ugly

"Go borrows a trick from BCPL: the semicolons that separate statements are in the formal grammar but..."

Thu, 06 May 2010 17:48:44 -0400

“Go borrows a trick from BCPL: the semicolons that separate statements are in the formal grammar but are injected automatically, without lookahead, by the lexer at the end of any line that could be the end of a statement.”

- Language Design FAQ

ranlib ala #jsapi

Tue, 04 May 2010 20:18:00 -0400

* cdleary goes to find out wtf ranlib is
cdleary: Yay!!
something bad that the Unix guys thought was really neato

cdleary: jim's answer not withstanding, on older unices, you had to "ranlib" your .a files (archives of object files) so that symbols within the library, but outside of objects could be resolved by the linker whether their definition appeared before or after first use in the library. At least, that's what my memory tells me. I was pretty green the last time I ran ranlib and it was actually...

...*necessary*
cdleary: Originally, 'ar' was a general purpose file-archiving program whose format just happened to be understood by the linker. But its use for anything but libraries gradually faded away.
And, originally, the .o files had to appear in the .a file in an order such that undefined symbols from earlier .o files would be resolved by later .o files, so the linker only needed to make a single pass through the .a file.
technically ar is still used by debian archives :)
I'm down with having simple tools that you use everywhere, but I'd argue that with those ordering requirements, the *net* simplicity wasn't optimized.
ah interesting -- wasn't aware .a had an internal order
Well, once you've ranlibbed something, the linker consults that, and there's no internal order required any more.
Anyway, the GNU binutils did away with that, and just built the index in ar, and made the archive mutation operations keep it up to date. So it's never mattered on GNU.

"By meditating effectively on anything you cultivate a keen alertness, a sharp and healthy mind. This..."

Mon, 03 May 2010 03:34:45 -0400

“By meditating effectively on anything you cultivate a keen alertness, a sharp and healthy mind. This meditation is about the breath.”

- Mindfulness of Breathing

"Many young girls define their self-worth according to how liked they are by others. They also equate..."

Sun, 02 May 2010 18:46:16 -0400

“Many young girls define their self-worth according to how liked they are by others. They also equate success with being liked. Failure, or even constructive criticism, leaves many girls feeling as if they’ve personally let someone down, or that a relationship is damaged. Failure can feel personal and global, raising the stakes for a risk.”

- Startups: An “Alpha Male Pissing-Contest?” | Fast Company

"Here, we try to speak clearly and in the simplest language possible because many of the people who..."

Tue, 27 Apr 2010 19:36:52 -0400

“Here, we try to speak clearly and in the simplest language possible because many of the people who read this forum are not as well-versed in these topics as we are, and many of whom would like to learn more.”

- http://lists.freebsd.org/pipermail/freebsd-performance/2003-June/000326.html

"If you want to provoke discussion, logic and detail are not your friends. Instead, don’t worry about..."

Mon, 26 Apr 2010 04:55:41 -0400

“If you want to provoke discussion, logic and detail are not your friends. Instead, don’t worry about loose ends and half-expressed ideas - just keep the audience’s interest and provide colour, and let them fill in the gaps later.”

- Wikibollocks: The Shirky Rules - Whimsley

"All enums implicitly extend java.lang.Enum. Since Java does not support multiple inheritance, an..."

Sun, 18 Apr 2010 19:12:28 -0400

“All enums implicitly extend java.lang.Enum. Since Java does not support multiple inheritance, an enum cannot extend anything else”

- Enum Types (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

Building the V8 shell on x64: set GCC_VERSION=44 scons arch=x64; g++ -Iinclude samples/shell.cc -o...

Fri, 09 Apr 2010 15:19:00 -0400

Building the V8 shell on x64:

set GCC_VERSION=44 scons arch=x64; g++ -Iinclude samples/shell.cc -o v8 libv8.a -lpthread

"It can only be avoided by using a separate terminal for program output which will be the case when..."

Wed, 07 Apr 2010 00:24:19 -0400

“It can only be avoided by using a separate terminal for program output which will be the case when we move to GDB/MI after the release. The only advice I can give you is “Don’t do that.”.”

- Re: error in process filter: gdb-starting: Unexpected `starting’ annotat

"Now the situation is more like the case where doSomething() was a final method in Foo — the..."

Sun, 04 Apr 2010 05:14:03 -0400

“Now the situation is more like the case where doSomething() was a final method in Foo — the compiler can convert the virtual method call into a direct dispatch (already an improvement) and, further, has the option to inline doSomething(), as well. (Converting a virtual method call to a direct method call is called monomorphic call transformation.)”

- Java theory and practice: Dynamic compilation and performance measurement

"Generics were introduced in Java in Java 5.0 to allow type-safe generic programming. Unlike arrays,..."

Wed, 24 Mar 2010 03:28:29 -0400

“Generics were introduced in Java in Java 5.0 to allow type-safe generic programming. Unlike arrays, generic classes are neither covariant nor contravariant. For example, neither List nor List is a subtype of the other:”

- Covariance and contravariance (computer science) - Wikipedia, the free encyclopedia

"Creating diagrams or pictures can allow you to connect ideas together on paper. Instead of having..."

Tue, 23 Mar 2010 03:58:30 -0400

“Creating diagrams or pictures can allow you to connect ideas together on paper. Instead of having linear notes, organized in a hierarchy, what if you had notes that showed the relationships between all the ideas you were learning?”

- How I Was Able to Ace Exams Without Studying | Zen Habits

"Veneers are small sections of code generated by the linker and inserted into your program. armlink..."

Tue, 09 Mar 2010 21:08:27 -0500

“Veneers are small sections of code generated by the linker and inserted into your program. armlink must generate veneers when a branch involves a destination beyond the branching range of the current state.”

- ARM Information Center

"As the code matures over time, the development repository gathers a number of merges and changesets...."

Tue, 02 Mar 2010 16:13:08 -0500

“As the code matures over time, the development repository gathers a number of merges and changesets. This history is important for the individual developer, but can be very difficult to review when sent upstream.”

- MqExtension - Mercurial

"Fortunately, the Java Platform provides a solution for that case by calling the close() method of..."

Mon, 01 Mar 2010 05:36:54 -0500

“Fortunately, the Java Platform provides a solution for that case by calling the close() method of the socket the thread is blocked in. In this case, if the thread is blocked in an I/O operation, the thread will get a SocketException exception, much like the interrupt() method causes an InterruptedException to be thrown.”

- Interrupting Java threads

I like the font 13px/1.6em ‘Lucida Grande’,Lucida,Verdana,sans-serif

Sat, 27 Feb 2010 23:37:50 -0500

I like the font 13px/1.6em ‘Lucida Grande’,Lucida,Verdana,sans-serif

"This idiom is sometimes summarized with the phrase “fork off and die"

Fri, 26 Feb 2010 00:44:21 -0500

“This idiom is sometimes summarized with the phrase “fork off and die””

- Daemon (computer software) - Wikipedia, the free encyclopedia

"Examples in this article are created using the AT&T assembly syntax used in GNU AS. […]..."

Thu, 25 Feb 2010 20:39:35 -0500

“Examples in this article are created using the AT&T assembly syntax used in GNU AS. […] GAS instructions generally have the form mnemonic source, destination.”

- X86 Assembly/GAS Syntax - Wikibooks, collection of open-content textbooks

"The C standard states that, after any parameters have been replaced with their possibly-expanded..."

Thu, 25 Feb 2010 14:46:52 -0500

“The C standard states that, after any parameters have been replaced with their possibly-expanded arguments, the replacement list is scanned for nested macros. Further, any identifiers in the replacement list that are not expanded during this scan are never again eligible for expansion in the future, if the reason they were not expanded is that the macro in question was disabled.”

- Macro Expansion - The GNU C Preprocessor Internals