According to some parts of ECL manual, necessary part of the library (that has been compiled by lisp) initialisation in C program is performing its initialisation as:
ecl_init_module(NULL, init_func_for_library);
In all examples provided first parameter is NULL.
What other values can it take and to what end? Certainly the parameter itself should have some meaning.
NB. In other parts of the manual, for performing initialisation, it is recommended to use read_VV instead. What does that do?
Inspecting the source code, we can see that NULL is bound to a variable named block; when it is NULL, a default, empty codeblock is used instead:
cl_object
ecl_init_module(cl_object block, void (*entry_point)(cl_object))
{
...
if (block == NULL)
block = ecl_make_codeblock();
...
}
Code blocks look like some sort of context/environment structures:
cl_object
ecl_make_codeblock()
{
cl_object block = ecl_alloc(t_codeblock);
block = ecl_alloc_object(t_codeblock);
block->cblock.self_destruct = 0;
block->cblock.locked = 0;
block->cblock.handle = NULL;
block->cblock.data = NULL;
block->cblock.data_size = 0;
block->cblock.temp_data = NULL;
block->cblock.temp_data_size = 0;
block->cblock.data_text = NULL;
block->cblock.next = ECL_NIL;
block->cblock.name = ECL_NIL;
block->cblock.links = ECL_NIL;
block->cblock.cfuns_size = 0;
block->cblock.cfuns = NULL;
block->cblock.source = ECL_NIL;
block->cblock.error = ECL_NIL;
block->cblock.refs = ecl_make_fixnum(0);
si_set_finalizer(block, ECL_T);
return block;
}
I guess in most cases, passing NULL is sufficient. Presumably you could call ecl_init_module with an existing code block to share to some state with another module; without a better understanding of how the interpreter works, this is however risky.
Related
Is it equal in flutter null safety?
if(widget.mapPickerController != null){
widget.mapPickerController!.mapMoving = mapMoving;
widget.mapPickerController!.mapFinishedMoving = mapFinishedMoving;
}
widget.mapPickerController?.mapMoving = mapMoving;
widget.mapPickerController?.mapFinishedMoving = mapFinishedMoving;
Both versions should end up doing the same thing. When null-safety enabled, ?. short-circuits the rest of the expression, so if the receiver is null, the rest of the expression (including the right-hand-side of the assignment) won't be evaluated. You can observe that in the following example:
class Foo {
int value = 0;
}
int bar() {
print('Called bar');
return 42;
}
void main() {
Foo? foo = null;
foo?.value = bar();
}
where running it generates no errors and shows that bar() is never called.
That said, the second version using ?. is much less clear (which is evident from the apparent confusion in the several deleted answers) and therefore probably should be avoided.
The best way would be to introduce a local variable:
final mapPickerController = widget.mapPickerController;
if (mapPickerController != null){
mapPickerController.mapMoving = mapMoving;
mapPickerController.mapFinishedMoving = mapFinishedMoving;
}
and then you don't need to use the null-assertion operator at all, and it's slightly more efficient since you check for null only once.
I'm currently trying to port some Specman code that takes certain actions based on whether a variable is part of an enumeration. In Specman the code looks something like this:
define COMP_STATES do_add, do_sub;
define WAIT_STATES wait_X, wait_Y;
defube RUN_STATES run_X, run_Y;
type my_states : [
do_add = 3'b000;
do_sub = 3'b001;
wait_X = 3'b010;
wait_Y = 3'b011;
run_X = 3'b100;
run_Y = 3'b101;
] (bits:3);
and then later:
if(state in [COMP_STATES, RUN_STATES]){
/* DO STUFF */
} else if(state in [WAIT_STATES]){
/* DO STUFF */
}
I now would like to do this in SystemVerilog but have hit a little bit of a snag. My currently best approach uses arrays:
my_state which_state[$] = {`COMP_STATES, `RUN_STATES};
int indexes[$] = which_state.get_index( index ) where ( index == state );
int num_indexes = indexes.size(); //If state doesn't exist in my_state then the returned array of indexes will be empty.
if(num_indexes > 0) begin /* DO STUFF */ end
But there has to be a more elegant and concise way? find_first_index comes to mind but I couldn't find what it would return in case no match was found.
There are a couple of ways you could do this. If you can depend on the encoding, then you can define your collection with a wildcard and use the wildcard equality operator or inside operator
let COMP_STATES = 3'b00?; // or parameter COMP_STATES = 3'b00?;
let RUN_STATES = 3'b01?; // or parameter RUN_STATES = 3'b01?;
let WAIT_STATES = 3'b10?; // or parameter WAIT_STATES = 3'b10?;
if (my_states inside {COMP_STATES,RUN_STATES})
...
else if (my_state ==? WAIT_STATES)
...
or you could just create an expression
module top;
enum bit [2:0] {
do_add = 3'b000,
do_sub = 3'b001,
wait_X = 3'b010,
wait_Y = 3'b011,
run_X = 3'b100,
run_Y = 3'b101
} my_states;
let COMP_STATES = my_states inside {do_add, do_sub};
let WAIT_STATES = my_states inside {wait_X, wait_Y};
let RUN_STATES = my_states inside {run_X, run_Y};
initial repeat(20) begin
std::randomize(my_states);
$write (my_states.name());
case(1)
COMP_STATES, RUN_STATES:
$display("=comp,run");
WAIT_STATES:
$display("-wait");
endcase
end
endmodule
Finally, if you were starting from scratch, I would suggest looking at tagged unions and their corresponding pattern matching conditional statements
I have written a function inside PostgreSQL which has the following code:
for (i = 0; i < 4; i++)
{
Datum dat_value = CStringGetDatum(inp->str[0][i]);
values[i] = datumCopy(dat_value,
stats->attrtype->typbyval,
stats->attrtype->typlen);
}
The input strings are {ALGERIA,ARGENTINA,BRAZIL,CANADA}. The code runs for ALGERIA,ARGENTINA but terminates abruptly for BRAZIL. When I investigated I found that inside datumCopy function, the statement after memcpy is not getting printed. I checked if palloc failed with (s == NULL) condition, but that seems to be not the reason. I think memcpy is failing. Any reason why? Thanks!
Datum
datumCopy(Datum value, bool typByVal, int typLen)
{
Datum res;
if (typByVal)
res = value;
else
{
Size realSize;
char *s;
if (DatumGetPointer(value) == NULL)
return PointerGetDatum(NULL);
realSize = datumGetSize(value, typByVal, typLen);
s = (char *) palloc(realSize);
printf ("Value : %s\n",DatumGetPointer(value));
memcpy(s, DatumGetPointer(value), realSize);
printf ("Not printing \n");
res = PointerGetDatum(s);
}
return res;
}
EDITED : Ok this is really wierd. When the input is one of {BRAZIL,PAKISTAN,FRANCE}, the code terminates abruptly. If I have other countries (I haven't tried extensively, but some countries), the code runs correctly.
EDITED 2 : Found the cause and rectified the issue. If we are passing C strings to datumCopy, we have to pass -2 for typLen parameter. I had been passing it incorrectly.
Thanks!
I have found the cause and rectified the issue.
If we are passing C strings to datumCopy, we have to pass -2 for typLen parameter. I had been passing it incorrectly.
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/sem.h>
#include<sys/ipc.h>
int sem_id;
void update_file(int number)
{
struct sembuf sem_op;
FILE* file;
printf("Inside Update Process\n");
/* wait on the semaphore, unless it's value is non-negative. */
sem_op.sem_num = 0;
sem_op.sem_op = -1; /* <-- Amount by which the value of the semaphore is to be decreased */
sem_op.sem_flg = 0;
semop(sem_id, &sem_op, 1);
/* we "locked" the semaphore, and are assured exclusive access to file. */
/* manipulate the file in some way. for example, write a number into it. */
file = fopen("file.txt", "a+");
if (file) {
fprintf(file, " \n%d\n", number);
fclose(file);
}
/* finally, signal the semaphore - increase its value by one. */
sem_op.sem_num = 0;
sem_op.sem_op = 1;
sem_op.sem_flg = 0;
semop( sem_id, &sem_op, 1);
}
void write_file(char* contents)
{
printf("Inside Write Process\n");
struct sembuf sem_op;
sem_op.sem_num = 0;
sem_op.sem_op = -1;
sem_op.sem_flg = 0;
semop( sem_id, &sem_op, 1);
FILE *file = fopen("file.txt","w");
if(file)
{
fprintf(file,contents);
fclose(file);
}
sem_op.sem_num = 0;
sem_op.sem_op = 1;
sem_op.sem_flg = 0;
semop( sem_id, &sem_op, 1);
}
int main()
{
//key_t key = ftok("file.txt",'E');
sem_id = semget( IPC_PRIVATE, 1, 0600 | IPC_CREAT);
/*here 100 is any arbit number to be assigned as the key of the
semaphore,1 is the number of semaphores in the semaphore set, */
if(sem_id == -1)
{
perror("main : semget");
exit(1);
}
int rc = semctl( sem_id, 0, SETVAL, 1);
pid_t u = fork();
if(u == 0)
{
update_file(100);
exit(0);
}
else
{
wait();
}
pid_t w = fork();
if(w == 0)
{
write_file("Hello!!");
exit(0);
}
else
{
wait();
}
}
If I run the above code as a c code, the write_file() function is called after the update_file () function
Whereas if I run the same code as a c++ code, the order of execution is reverse... why is it so??
Just some suggestions, but it looks to me like it could be caused by a combination of things:
The wait() call is supposed to take a pointer argument (that can
be NULL). Compiler should have caught this, but you must be picking
up another definition somewhere that permits your syntax. You are
also missing an include for sys/wait.h. This might be why the
compiler isn't complaining as I'd expect it to.
Depending on your machine/OS configuration the fork'd process may
not get to run until after the parent yields. Assuming the "wait()"
you are calling isn't working the way we would be expecting, it is
possible for the parent to execute completely before the children
get to run.
Unfortunately, I wasn't able to duplicate the same temporal behavior. However, when I generated assembly files for each of the two cases (C & C++), I noticed that the C++ version is missing the "wait" system call, but the C version is as I would expect. To me, this suggests that somewhere in the C++ headers this special version without an argument is being #defined out of the code. This difference could be the reason behind the behavior you are seeing.
In a nutshell... add the #include, and change your wait calls to "wait(0)"
I'm using Firefox + searchbastard addon to do a multi-search on shopping search engines.The pages are part of a frame. This works just fine for all sites I tried so far except for shopmania.com.
If I use noscript to forbid scripts from the shopmania domain name then everything stays in place but the part of the website elements become nonresponsive. I know there is an option in Firefox to force links that open in a new window to open in a new tab. Is there something similar to prevent websites from popping out of frame? Maybe a Firefox addon that blocks these requests?
Or at least can someone please tell me what is causing only this website to act like this?
EDIT: What tool can i use to pause firefox OR javascript and stepthrough code like in c++ ? I tried a javascript debugger and firebug. They don't help but i'm probably not using them right..
EDIT2: I tried this greasemonkey script : https://userscripts.org/scripts/show/92424. It does not work so i guess it isn't because of 'target' attribute
This is wrong. I'm guessing you're using a plugin to capture and override the output some site gives you. I'm pretty sure this violates their ToS and it's not a very nice thing to do in general.
JavaScript is not designed to allow this kind of meddling. It's patchy at best.
If you want to use the data from a website, to aggregate or display in some manner, use their public API. If they don't have a public API they probably don't want you to use their service in such a manner.
The solution : I took the script from Stop execution of Javascript function (client side) or tweak it and modified it to search for the tag that has in it top.location = location and then appended a new script with the if (top != self) {top.location = location;} line commented . Being a js total newbie i don't know if it's the most elegant choice but it soves the prob. Special thanks to Tim Fountain.
I will leave this open just in case someone else will suggest a better solution, for my and others's education. Again thanks for the help.
Below is the code:
// ==UserScript==
// #name _Replace evil Javascript
// #run-at document-start
// ==/UserScript==
/****** New "init" function that we will use
instead of the old, bad "init" function.
*/
function init () {
/* //changing stuff around here
var newParagraph = document.createElement ('p');
newParagraph.textContent = "I was added by the new, good init() function!";
document.body.appendChild (newParagraph); */
<!--//--><![CDATA[//><!--
document.getElementsByTagName("html")[0].className+=" js "+(navigator.userAgent.toLowerCase().indexOf("webkit")>=0?"webkit":navigator.userAgent.toLowerCase().indexOf("opera")>=0?"opera":"");
for(i in css3_tags="abbr|header|footer".split("|")){document.createElement(css3_tags[i]);}
var PATH = "http://www.shopmania.com";
var PATH_STATIC = "http://im4.shopmania.org";
var PATH_SELF = "http://www.shopmania.com/";
var RETURN = "http%3A%2F%2Fwww.shopmania.com%2F";
var DOMAIN_BASE = "shopmania.com";
var SUBDOMAINS_FORCE_FILES_JS = "aff.remote,biz.remote,my.remote,cp.remote,cp.register_quick,cp.account_details,partner.remote,site.recommend,site.remote,site.feedback,site.report_problem,site.report,site.cropper";
var URL_REWRITE_MAPPING_JS = "cmd,section,do,option|feed,mode,option|forgot,section|info,page|login,section|logout,section|new_password,section,code|settings,section|shopping,param_main,param_sec|site,store_str_key|register,section|unsubscribe,section|agentie,store_str_key,id|brand,manuf_str_key|brands,letter|build,type,param_main,param_sec|compare,online|confirm,section|edit,section|deal,deal|dictionary,online|home,section|link_accounts,section|profile,user|reactivate,section|searches,letter|signup,section|rs_agent,store_str_key|rs_list,param_main,param_sec|rs_view,ad|agents,state|complex_list,param_main|complex_view,complex|list,cat|ad,a|map,option|my_ads,section|my_alerts,section";
var SVR_SITE_ID = "us";
var CONTEXT = "c5b27de70340c97a94092a43bd34b2b8";
var link_close = "Close";
var txt_loading = "Loading...";
var form_is_submitted = 0;
var search_is_focused = 0;
// Overlay object
var OL;
var DB;
var iframe_cnt = "";
// Facebook post to user's Wall action
var FACEBOOK_WALL_FEED_SIGNUP = "";
var SITENAME = "ShopMania";
//if (top != self) {top.location = location;} // SIT!
var comps = new Array(); comps['all'] = 0;var comps_cat_titles = new Array(); var views = new Array(); views['auto'] = 0; views['prod'] = 0; views['realestate'] = 0; views['classifieds'] = 0; views['all'] = 0; var search = new Array(); search['all'] = 0; search['prod'] = 0;
var favs = new Array(); favs['all'] = 0; favs['prod'] = 0; favs['store'] = 0; favs['manuf'] = 0; favs['other'] = 0; favs['realestate'] = 0; favs['auto'] = 0;
function addCss(c){var b=document.getElementsByTagName("head")[0];var a=document.createElement("style");a.setAttribute("type","text/css");if(a.styleSheet){a.styleSheet.cssText=c}else{a.appendChild(document.createTextNode(c))}b.appendChild(a)};
addCss(".lzl {visibility: hidden;}");
var RecaptchaOptions = { theme : 'clean' };
//--><!]]>
}
/*--- Check for bad scripts to intercept and specify any actions to take.
*/
checkForBadJavascripts ( [
[false, /top.location = location/, function () {addJS_Node (init);} ]
] );
function checkForBadJavascripts (controlArray) {
/*--- Note that this is a self-initializing function. The controlArray
parameter is only active for the FIRST call. After that, it is an
event listener.
The control array row is defines like so:
[bSearchSrcAttr, identifyingRegex, callbackFunction]
Where:
bSearchSrcAttr True to search the SRC attribute of a script tag
false to search the TEXT content of a script tag.
identifyingRegex A valid regular expression that should be unique
to that particular script tag.
callbackFunction An optional function to execute when the script is
found. Use null if not needed.
*/
if ( ! controlArray.length) return null;
checkForBadJavascripts = function (zEvent) {
for (var J = controlArray.length - 1; J >= 0; --J) {
var bSearchSrcAttr = controlArray[J][0];
var identifyingRegex = controlArray[J][1];
if (bSearchSrcAttr) {
if (identifyingRegex.test (zEvent.target.src) ) {
stopBadJavascript (J);
return false;
}
}
else {
if (identifyingRegex.test (zEvent.target.textContent) ) {
stopBadJavascript (J);
return false;
}
}
}
function stopBadJavascript (controlIndex) {
zEvent.stopPropagation ();
zEvent.preventDefault ();
var callbackFunction = controlArray[J][2];
if (typeof callbackFunction == "function")
callbackFunction ();
//--- Remove the node just to clear clutter from Firebug inspection.
zEvent.target.parentNode.removeChild (zEvent.target);
//--- Script is intercepted, remove it from the list.
controlArray.splice (J, 1);
if ( ! controlArray.length) {
//--- All done, remove the listener.
window.removeEventListener (
'beforescriptexecute', checkForBadJavascripts, true
);
}
}
}
/*--- Use the "beforescriptexecute" event to monitor scipts as they are loaded.
See https://developer.mozilla.org/en/DOM/element.onbeforescriptexecute
Note that it does not work on acripts that are dynamically created.
*/
window.addEventListener ('beforescriptexecute', checkForBadJavascripts, true);
return checkForBadJavascripts;
}
function addJS_Node (text, s_URL, funcToRun) {
var D = document;
var scriptNode = D.createElement ('script');
scriptNode.type = "text/javascript";
if (text) scriptNode.textContent = text;
if (s_URL) scriptNode.src = s_URL;
if (funcToRun) scriptNode.textContent = '(' + funcToRun.toString() + ')()';
var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement;
//--- Don't error check here. if DOM not available, should throw error.
targ.appendChild (scriptNode);
}
there are some escaping issues with the cdata part in the code.So SO does not allow me to post the code.
EDIT: fixed