I see
(in Version 1.2.49, Linux Foundation ):
png_uint_32 png_get_iCCP(png_structp png_ptr, png_infop info_ptr, png_charpp name, int * compression_type, png_charpp profile, png_uint_32 * proflen);
And (in version 1.6.37):
png_uint_32 png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr, png_charpp name, int *compression_type, png_bytepp profile, png_uint_32 *proflen);
The main difference is the incompatible change of the fifth parameter, from type char ** to type png_byte **.
Now, I definitely accept that the newer form is correct.
But that doesn't help if you want to be able to build with any version of the library.
My basic question is: When did this change take place?
One annoying part of this change is that it went unnoted in the API documentation, probably in part because said documentation doesn't even mention types.
I figure the compile-time test will look something like:
#if (PNG_LIBPNG_VER>=10402)
but that I would need to know what number to put in.
I figure my alternative is to write some autoconf tests.
As an additional question: Are there any other incompatible API changes in libpng's history?
Related
I am looking at some old MetaEditor4 / MQL4 code, where a local variable was declared twice:
......
1 int start()
2 {
3 if (1==2)
4 {
5 double myVar = 1;
6 } else
7 {
8 double myVar = 2;
9 }
10 return;
11 }
.......
The compilation process in MetaEditor, version 5.00, build 1601, fails with:
'myVar' - variable already defined in line 8.
If I remove the line 8, the compilation goes well.
My questions are:
1. Is there any option in MetaEditor that tolerates the multiple declaration of a local variable?
2. In previous versions of MetaTrader Terminal 4 / MetaEditor and .MQ4 code: was it possible to declare a local variable more than once in such a situation?
3. The MetaEditor has the version 5.00, build 1601, but the extension of the code is .mq4 and it was installed together with the MetaTrader Terminal software MetaTrader4 ( from FXCM ). Therefore I assume I can still use .MQ4 code with it. Is there any chance to get a pure MQL4 installation from somewhere?
Whenever I install mt4 ( from e.g.: mt4 download), it ends up
with the mt5 installer.
Prologue:
The worlds of MQL4 evolve. One may try to circumvent this fact, but finally, at one's own disappointment, attempts to avoid evolution will sooner or later go in vain.
Having been thrown into a need to re-engineer code-base spanning a few man*decades in size, I can tell you many stories about what worked and what did not.
An "Old code" v/s a New-MQL4.56789
If just one thing ought be taken from this, never try to "circumvent" New-MQL4, but rather review the code and refactor the "Old code" - this is a way safer way to survive ( way longer ).
Yes, there are chances ( zero warrants, just a few chances left temporarily on the table ) the new compiler version will remain able to generate an executable version of the code, but given a new set of rules have already come in the city, the game will not last long.
Ad 1 + 2 )Compiler still tolerates multiple declarations, but not in one scope
If new version of a compiler defined that any variable is declared only relative to it's scope of validity, the serious programmer ought take this as a general principle. The code above actually has other problem, right nailed to the scope-of-validity:
2 ...
3 if ( 1 == 2 ) {
4 ...
5 double myVar = 1; // myVar declared & known |since HERE >
6 ... // masking any other,|known HERE :
7 ... // |known HERE :
8 } else // |till HERE . Undef further
9 {
10 ...
11 double myVar = 2; // myVar declared & known |since HERE >
12 // masking any other,|known HERE :
13 ... // |known HERE :
14 } // |till HERE . Undef further
so, if there were any _global_ scope'd variable with the same name myVar, it will not be "visible" during an existence of locally declared variable, wearing the same name.
Finally, having the code-execution escaped from any of the lines 8 or 14 further, the locally there declared variable double myVar simply ceased to exist anymore and this behaviour is principally correct ( and the "older" compiler releases were tolerating a sort of dangerous habit of side-effects, during years of tolerating scope-of-validity spillover(s), so it was the high time to clean the rules, so as to meet a fair level of C/S standards.
Ad 3) language receives a lot from MQL5, even if not used in MQL4
Yes, MetaEditor will correctly compile a MQL4 code into .mq4 code-execution format, no problem here. Even an auto-update process started to go independently from MT4 Terminal platform (auto-)updates ( so you will quite often see new Help file coming and enforced re-compilation of all your localhost visible .MQ4 assets into updated .EX4 format, so "Do not panic."
Better never install a Broker-agnostic MT4, always go to your Broker's Support and get installation package & help from your Broker. This is business relation you have signed in a contract, so keep these strings as you are going to trade your money on a table they operate under the set Terms & Conditions. Some Brokers have means of platform customisations, so rather benefit from their custom settings that will match their Server-side automation.
It is more a question of economy of R&D efforts. ( May read a lot about language components injected from the MQL5 domain in the IDE Editor MQL4 Help ). This is a natural will of the product design strategy, not to double efforts on a dual-line. Without doubts, there are many details the Help file could be improved and better maintained, the common sense here is to live with the facts and re-learn what newly introduced features remain neutral for the MQL4 code base and what new things may actually help one a lot in aspects, where older compilers were short in powers.
If one objects that some compiler / platform re-design steps were bad, I would agree on a single-thread, platform-critical, potentially blocking, concentration of executing all the CustomIndicator-s in just one SPoF-thread.
But C'est La Vie, until system architects will not review this SPoF, the platform will remain susceptible to crashes from this feature, but the ball is on the other side of the court and a change will have to be implemented there.
the code might be run with 'strict' or non-strict mode.
strict means that variable must be declared within its scope, non-strict - all the mess that you have now.
so put #property strict at the beginning of the file
open a demo account somewhere and install mt4 there. demo can be valid for 30 days only with registration via web-site of a broker or with unlimited and demo opened from mt4 (example - Alpari)
In a mozille extension I run:
SecSess.Logger.info("ctypes test");
Components.utils.import("resource://gre/modules/ctypes.jsm");
SecSess.Logger.info("1");
this.lib = ctypes.open("libcrypto.so");
SecSess.Logger.info("2");
var a = new Uint8Array(1<<10);
SecSess.Logger.info("3");
var ptr = new ctypes.uint8_t.ptr(a.buffer);
SecSess.Logger.info("4");
Why this ugly logging after each step you might ask? Well this code fails without showing me an error. (or at least I can't find the error message)
This is printed:
ctypes test
1
2
3
So the 5th log message is never printed which means the following statement never completes:
var ptr = new ctypes.uint8_t.ptr(a.buffer);
This is a simplified version of some old code I have to work with and which I also found online as being valid. However it doesn't work. This add-on wasn't developped using the new SDK with jpm. Quite frankly I don't know how and when it was developped but I need to run some tests on it. It comes with a few source files ordered in a components and a modules directory and a chrome.manifest and install.rdf in the root. I copied these files to the extension directory of Mozilla in order for it to work. The extension executes but there seems to be a problem with ctypes. Aren't ctypes fully supported anymore or are these old style add-on no longer valid for the modern Firefox?
Regards,
Roel
I think they landed a a patch to disallow making a pointer from buffers. I'll double check.
Edit:
Ah per this: https://developer.mozilla.org/en-US/docs/Mozilla/js-ctypes/Using_js-ctypes/Working_with_ArrayBuffers, you don't have to wrap it with a ctypes.uint8_t.ptr just pass it like a.buffer to wherever you need it. :)
I'm just learning F#, and setting up a FAKE build harness for a hello-world-like application. (Though the phrase "Hell world" does occasionally come to mind... :-) I'm using a Mac and emacs (generally trying to avoid GUI IDEs by preference).
After a bit of fiddling about with documentation, here's how I'm invoking the F# compiler via FAKE:
let buildDir = #"./build-app/" // Where application build products go
Target "CompileApp" (fun _ -> // Compile application source code
!! #"src/app/**/*.fs" // Look for F# source files
|> Seq.toList // Convert FileIncludes to string list
|> Fsc (fun p -> // which is what the Fsc task wants
{p with //
FscTarget = Exe //
Platform = AnyCpu //
Output = (buildDir + "hello-fsharp.exe") }) // *** Writing to . instead of buildDir?
) //
That uses !! to make a FileIncludes of all the sources in the usual way, then uses Seq.toList to change that to a string list of filenames, which is then handed off to the Fsc task. Simple enough, and it even seems to work:
...
Starting Target: CompileApp (==> SetVersions)
FSC with args:[|"-o"; "./build-app/hello-fsharp.exe"; "--target:exe"; "--platform:anycpu";
"/Users/sgr/Documents/laboratory/hello-fsharp/src/app/hello-fsharp.fs"|]
Finished Target: CompileApp
...
However, despite what the console output above says, the actual build products go to the top-level directory, not the build directory. The message above looks like the -o argument is being passed to the compiler with an appropriate filename, but the executable gets put in . instead of ./build-app/.
So, 2 questions:
Is this a reasonable way to be invoking the F# compiler in a FAKE build harness?
What am I misunderstanding that is causing the build products to go to the wrong place?
This, or a very similar problem, was reported in FAKE issue #521 and seems to have been fixed in FAKE pull request #601, which see.
Explanation of the Problem
As is apparently well-known to everyone but me, the F# compiler as implemented in FSharp.Compiler.Service has a practice of skipping its first argument. See FSharp.Compiler.Service/tests/service/FscTests.fs around line 127, where we see the following nicely informative comment:
// fsc parser skips the first argument by default;
// perhaps this shouldn't happen in library code.
Whether it should or should not happen, it's what does happen. Since the -o came first in the arguments generated by FscHelper, it was dutifully ignored (along with its argument, apparently). Thus the assembly went to the default place, not the place specified.
Solutions
The temporary workaround was to specify --out:destinationFile in the OtherParams field of the FscParams setter in addition to the Output field; the latter is the sacrificial lamb to be ignored while the former gets the job done.
The longer term solution is to fix the arguments generated by FscHelper to have an extra throwaway argument at the front; then these 2 problems will annihilate in a puff of greasy black smoke. (It's kind of balletic in its beauty, when you think about it.) This is exactly what was just merged into the master by #forki23:
// Always prepend "fsc.exe" since fsc compiler skips the first argument
let optsArr = Array.append [|"fsc.exe"|] optsArr
So that solution should be in the newest version of FAKE (3.11.0).
The answers to my 2 questions are thus:
Yes, this appears to be a reasonable way to invoke the F# compiler.
I didn't misunderstand anything; it was just a bug and a fix is in the pipeline.
More to the point: the actual misunderstanding was that I should have checked the FAKE issues and pull requests to see if anybody else had reported this sort of thing, and that's what I'll do next time.
One of my users at a large university (with, I imagine, the aggressive security settings that university IT departments general have on their computers) is getting an empty string returned by Windows XP for CSIDL_COMMON_APPDATA or CSIDL_PERSONAL. (I'm not sure which of these is returning the empty string, because I haven't yet examined his computer to see how he's installed the software, but I'm pretty sure it's the COMMON_APPDATA...)
Has anyone encountered this or have suggestions on how to deal with this?
Here's the Delphi code I'm using to retrieve the value:
Function GetSpecialFolder( FolderID: Integer):String;
var
PIDL: PItemIDList;
Path: array[0..MAX_PATH] of Char;
begin
SHGetSpecialFolderLocation(Application.Handle, FolderID, PIDL);
SHGetPathFromIDList(PIDL, Path);
Result := Path;
end; { GetSpecialFolder }
ShowMessage(GetSpecialFolder(CSIDL_COMMON_APPDATA)); <--- This is an empty string
Edit:
Figuring out this API made me feel like I was chasing my tail - I went in circles trying to find the right call. This method and others similar to it are said to be deprecated by Microsoft (as well as by a earlier poster to this question (#TLama?) who subsequently deleted the post.) But, it seems like most of us, including me, regularly and safely ignore that status.
In my searches, I found a good answer here on SO from some time ago, including sample code for the non-deprecated way of doing this: what causes this error 'Unable to write to application file.ini'.
If you want to find out why an API call is failing you need to check the return values. That's what is missing in this code.
You need to treat each function on its own merits. Read the documentation on MSDN. In the case of SHGetSpecialFolderLocation, the return value is an HRESULT. For SHGetPathFromIDList you get back a BOOL. If that is FALSE then the call failed.
The likely culprit here is SHGetSpecialFolderLocation, the code that receives the CSIDL, but you must check for errors whenever you call Windows API functions.
Taking a look at the documentation for CSIDL we see this:
CSIDL_COMMON_APPDATA
Version 5.0. The file system directory that contains application data for all users. A typical path is C:\Documents and Settings\All
Users\Application Data. This folder is used for application data that
is not user specific. For example, an application can store a
spell-check dictionary, a database of clip art, or a log file in the
CSIDL_COMMON_APPDATA folder. This information will not roam and is
available to anyone using the computer.
If the machine has a shell version lower than 5.0, then this CSIDL value is not supported. That's the only documented failure mode for this CSIDL value. I don't think that applies to your situation, so you'll just have to see what the HRESULT status code has to say.
I am trying to run xUnit tests (from an F# module, if it makes any difference) using TestDriven.NET, but whatever I do I get this error:
It looks like you're trying to execute an xUnit.net unit test.
For xUnit 1.5 or above (recommended):
Please ensure that the directory containing your 'xunit.dll' reference also contains xUnit's
test runner files ('xunit.dll.tdnet', 'xunit.runner.tdnet.dll' etc.)
For earlier versions:
You need to install support for TestDriven.Net using xUnit's 'xunit.installer.exe' application.
You can find xUnit.net downloads and support here:
http://www.codeplex.com/xunit
I tried following the suggestions, i.e. I copied the files
xunit.dll.tdnet
xunit.extensions.dll
xunit.gui.clr4.exe
xunit.runner.tdnet.dll
xunit.runner.utility.dll
xunit.runner.utility.xml
xunit.xml
to the folder with xunit.dll and I ran xunit.installer.exe. How can I get it to work?
I just figured out that I forgot to make the test a function in F# (so it was just a value). The error message can't be more misleading though!
You have two problems:
your Fact is broken:-
If you hover over the
please work
bit, you'll see something like: unit -> int
For a Fact to be picked up by an xUnit runner, it needs to yield `unit (void).
Hence, one key thing to get right first is to not return anything. In other words, replace your 123 with () (or an Assertion).
You can guard against this by putting a :unit stipulation on the test:-
[<Fact>]
let ``please work`` () : unit = 123
This will force a compilation error.
TestDriven.NET is reporting it cannot find the xunit.tdnet modules
It's critical to get step 1 right first. Then retry and the problem should be gone
If it remains...
Either try the VS-based runner which should work as long as it's installed and xunit.dll is getting to your output dir or look at the docs for your version of TD.NET for detailed troubleshooting notes (exec summary is if the .tdnet file was in your out dir or you undo and redo the xunit.installer from the folder containing the packages it should just work, esp if you are on latest)