Is creating a file-tree a built-in feature of q? - kdb

I've seen in .Q sources (q.k) that applying a dir-symbol to empty symbol (or to its sub-dir symbol) creates a full folders-tree, try this:
`:dir1 `
Is this behavior documented somewhere? Or is this a feature for internal use only and is subject to change?

Its because we can use key/value to file-symbol I think all other stuff works. Applying to all (`), and to the specific key works as in usual dictionary.

Related

gcc precompiler directive __attribute__ ((__cleanup__)) vs ((cleanup)) (with vs without underscores?)

I'm learning about gcc's cleanup attribute, and learning how it calls a function to be run when a variable goes out of scope, and I don't understand why you can use the word "cleanup" with or without underscores. Where is the documentation for, or documentation of, the version with underscores?
The gcc documentation above shows it like this:
__attribute__ ((cleanup(cleanup_function)))
However, most code samples I read, show it like this:
__attribute__ ((__cleanup__(cleanup_function)))
Ex:
http://echorand.me/site/notes/articles/c_cleanup/cleanup_attribute_c.html
http://www.nongnu.org/avr-libc/user-manual/atomic_8h_source.html
Note that the first example link states they are identical, and of course coding it proves this, but how did he know this originally? Where did this come from?
Why the difference? Where is __cleanup__ defined or documented, as opposed to cleanup?
My fundamental problem lies in the fact that I don't know what I don't know, therefore I am trying to expose some of my unknown unknowns so they become known unknowns, until I can study them and make them known knowns.
My thinking is that perhaps there is some globally-applied principle to gcc preprocessor directives, where you can arbitrarily add underscores before or after any of them? -- Or perhaps only some of them? -- Or perhaps it modifies the preprocessor directive or attribute somehow and there are cases where one method, with or without the extra underscores, is preferred over the other?
You are allowed to define a macro cleanup, as it is not a name that is reserved to the compiler. You are not allowed to define one named __cleanup__. This guarantees that your code using __cleanup__ is unaffected by other code (provided that other code behaves, of course).
As https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute-Syntax explains:
You may optionally specify attribute names with __ preceding and following the name. This allows you to use them in header files without being concerned about a possible macro of the same name. For example, you may use the attribute name __noreturn__ instead of noreturn.
(But note that attributes are not preprocessor directives.)

overpass-api: regex on keys

According to http://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL
queries can use regular expressions on both the values and the keys. While I have no trouble using regex on the values, I'm having a problem with the keys.
The example on the wiki referenced above says (among other examples):
/* finds addr:* tags with value exactly "Foo" */
node[~"^addr:.*$"~"^Foo$"];
So, that's an example of using regex on the keys and the values.
What I am interested in is the name key. Specifically the name:en key. There are a couple problems with searching by name. Not all names are in English, and for those nodes/way/relations whose names are not in English, there is no guarantee there will be a name:en tag with an English version of the name.
In general, there is no way to know in advance if the name will be in English or that there is a name:en tag. If you only ask for name or name:en, you run the risk of finding no hit. (Of course, searching for both is no guarantee of success, either.)
I have a case where I know name fails, but name:en succeeds. That is my test case. I can query the overpass-api.de/api/interpreter using this:
[out:json][timeout:25][bbox:33.465530,36.156006,33.608615,36.574516];
(
node[name~"duma",i][place];
way[name~"duma",i][place];
>;
relation[name~"duma",i][place];
node["name:en"~"duma",i][place];
way["name:en"~"duma",i][place];
>;relation["name:en"~"duma",i][place];
);
out center;
see it on overpass
and it works fine ("duma" is not found through name, but it is found with name:en), but I find it lengthy and somewhat repetitive.
I would like to use a regular expression involving the name and name:en tags, but either the server does not understand the query or I simply am using an incorrect regex.
Using the example shown in the wiki: node[~"^addr:.*$"~"^Foo$"]
I have tried:
[~"name|name:en"~"duma",i]
[~"name.*"~"duma",i]
[~"^name.*$"~"duma",i]
and several others. I even mimicked the example with [~"^name:.*"~"duma",i] just to see if anything would be returned.
Does overpass-api.de recognize regular expressions on the keys or do I just have the regex wrong? I don't get an error from overpass-api.de, just the coordinates of the bbox and an empty result. It's usually very strict about reacting to a poortly formatted query. Thanks in advance.
That's really a bug in the Overpass API implementation concerning case-insensitive key regex matching, see this Github ticket for details.
For the time being, you can already test the patch on the development box:
http://overpass-turbo.eu/s/b1l
BTW: If you don't need case-insensitive regexp matching, this should already work on overpass-api.de as of today.

How can I use a simpler link syntax in org-mode?

I'd like to have links with the syntax [[foo bar]] go to files with the name foo bar.org. This would make using org-mode much more like using a personal local wiki.
Is this possible without breaking existing link functionality? I'd also ideally still be able to export to html, etc. with standard org-mode tools.
The best I've been able to do is something like: (setq org-link-abbrev-alist '(("o" . "file:%s.org")))
This lets me use the syntax [[o:foo bar]], but that is more verbose, and looks distractingly ugly inline. For example: The quick brown o:fox jumps over the o:lazy_dog. And [[o:foo bar][foo bar]] is even more verbose to type and edit (though it reads fine in org mode).
I don't have a ready made solution and am not a programmer, but this part is self-documenting in org.el, you can write a dedicated link search function. I cite:
"List of functions to execute a file search triggered by a link.
Functions added to this hook must accept a single argument, the search
string that was part of the file link, the part after the double
colon. The function must first check if it would like to handle this
search, for example by checking the `major-mode' or the file
extension. If it decides not to handle this search, it should just
return nil to give other functions a chance. If it does handle the
search, it must return a non-nil value to keep other functions from
trying.
Each function can access the current prefix argument through the
variable `current-prefix-arg'. Note that a single prefix is used to
force opening a link in Emacs, so it may be good to only use a numeric
or double prefix to guide the search function.
In case this is needed, a function in this hook can also restore the
window configuration before `org-open-at-point' was called using:
(set-window-configuration org-window-config-before-follow-link)")
See also Hyperlinks :: Custom Searches # gnu.org

How can I jump only to the exact function name with etags?

I wanted to find the following function with etags:
dt()
but as I go through the tag table, I keep hitting functions with dt in their names, like
widthThing1()
widthThing2()
...
making the definition of dt() extremely difficult to find.
Is there some way to search only for the exact function that I'm searching for with etags?
Open up your TAGS file and see what it is actually indexing (which will vary by language, of course).
For instance, if the relevant entry looked like this:
function ds(^?6140,232332
Then you could use function ds( (or potentially just ds( ) as your search term, to ensure that you weren't matching other functions.
You could omit the "function" part of that, except that typing SPC at the find-tag prompt will invoke TAG completion. You could avoid that by typing C-qSPC instead, or alternatively utilise find-tag-regexp bound to C-M-. which does not have the completion binding.
So C-M-.SPC ds( RET might be convenient.
You may also want to look at the etags-select library and binding M-. to etags-select-find-tag, which I find provides a much better interface.
You can get that from the EmacsWiki, or Marmalade:
http://www.emacswiki.org/emacs/EtagsSelect
http://marmalade-repo.org/packages/etags-select
Packages like Icicles and Helm also provide alternative interfaces. You can start reading at http://emacswiki.org/emacs/EmacsTags

Comments for Function in Emacs

I'm looking for a way to generate and insert header comment blocks above my functions in Emacs (in any mode), with the default contents of the comment automatically based on the function's signature (i.e. the correct number of #param place-holders).
Doxymacs is a nice candidate. But I prefer another way works without the necessary libs. Can anyone recommend some others ways for adding smart comments for functions in Emacs? Thanks.
Edit:
Now I found this: http://nschum.de/src/emacs/doc-mode/, but it seems that it does not work well after I require it into my .emacs and add hook for js-mode. Doesn't it support js functions ?
I don't know of any general-purpose approach.
Csharp-mode has a defun that is bound to / , which tries to generate comments appropriate for C#. The way it works: Every time you type a slash, it looks to see if it is the third slash in a row. (In C#, three slashes are used to denote comments that produce documentation). If it is the third slash, then it looks at the surrounding text and inserts a comment skeleton or fragment that is appropriate.
It is not generalized in any way to support javascript or other language syntaxes. But you might be able to build what you want, if you start with that.
here's the excerpt:
http://pastebin.com/ATCustgi
I've used doxymacs in the past and I've found it useful
http://doxymacs.sourceforge.net/