I tried to create an F# record type containing a FlowDocument in Visual Studio 2012 RC somewhat like this:
module RecordTest =
open System.Windows.Documents
type TestRecord =
{
TestName : FlowDocument
}
let test = { TestName = new FlowDocument () }
The strange thing is, this does not work for me. Visual Studio tells me: The record label TestName is not defined. and hovering over the type definition of TestRecord does not reveal a tool tip. If I change the type of TestName to e.g. string, everything works as it should.
For FlowDocument, a reference to PresentationFramework.dll is needed.
What's going on here?
Anybody able to get this working?
Thanks.
Future readers: if something seems unclear or inconsistent with the question, answer ans comments, please note that the original question (to which the answer and some of the comments refer) had different indentation (which affects the code). I am not rolling back the edit, because some of the comments do refer to the indented version. -- July 31st, Ramon Snir
I got this to work by indenting everything after the first line (NB this has now been done in the code sample in the question), and adding references to PresentationCore, System.Xaml and WindowsBase as well as PresentationFramework.
Not sure this explains your error message, however!
I'm using VS2010 so the behaviour may be different.
Related
Following are the few F# styles of variable naming. I am able to refer first two variable in my F# editor (through intelisense) but not the third variable. This is my first program using F# and just started crawling.
let simple="simple"
let ``let``=10
let ``son's birthday`` ="12/12/2012"
I have reported this issue to Microsoft F# team and they responded with following note "Thanks for the bug report! I can reproduce the issue here, we will follow up on our side with a fix."
I'm trying to connect my Windows XP program (Lazarus) to my Ubuntu postgres server.
When the Lazarus program runs, it seems to compile fine but I get this error:
Project ... raised exception class 'RunError(211)'.
Then it terminates execution (and I don't see any output), and opens up a file customform.inc. In that file, it shows a procedure procedure TCustomForm.DoCreate; where it highlights a line: if Assigned(FOnCreate) then FOnCreate(Self);
I believe this is one of the system's files.
I never get to see any output.
What could this be? Thanks!
MORE INFO:
I've narrowed down the error to this line:
dbQuery_Menu.SQL.Text:='Select * From "tblMenus"';
dbQuery_Menu.Open;
the exception is triggered when the OPEN statement gets executed.
BTW, dbQuery_Menu is defined as a TSQLQuery component.
Clueless! :(
Run error 211 appears when you try to call an abstract method. Check this link from more information on FreePascal/Lazarus runtime errors.
Since you say all is done by code and you have no visual components, the problem probably lies in your code trying to use an ancestor component which has not overriden the Open method. You should be able to solve this by using the correct descendant component.
Another possibility, although I would strongly recommend to avoid this one, is to override the Open method yourself. It should be avoided because if you are using an ancestor component then you probably would have to override more abstract methods.
HTH
After nearly 5 days I found the answer. Many thanks to all thos e ho have contributed with their ideas ESPECIALLY RRUZ, RBA and Guillem Vicens. there are other related posts all connected to getting the FIRST Lazarus program working with PostgreSQL.
Summary.
The biggest mistake I made here was that I used the TSQLConnection component. Don't do this. Instead use the TPQConnection.
Everything is done through code. We're not using any draggable components from the top tab.
Don't rely on the Lazarus docs (wiki) at least for working with PG DBs.. It is outdated. Some of the examples can be pretty misleading.
Make sure that fields have some default values. For example, if a Boolean field has no true or false (t/f) set, this may lead to errors.
And that's it! I hope many postgres+Lazarus newbies will find this useful.
From here - http://www.network-theory.co.uk/docs/postgresql9/vol2/SQLSTATEvsSQLCODE.html - -211 (ECPG_CONVERT_BOOL) This means the host variable is of type bool and the datum in the database is neither 't' nor 'f'. (SQLSTATE 42804)
I just splited a project in a few libraries.
And I have the strange error in the title.
I can't explain myself why it is the case.
Also, this error used to show up only in FSI.exe
I thought it was because of pb with loading dll in fsi but there is more to this.
It might be a stupid error (probably is..) but if anyone encoutered this sybillin error message before and knows what happens, I'd be glad to hear it.
UPDATE
I thought it was namespace issues, but it is not.
This issue is very odd. Please ignore it if you did not experienced it. I am still trying to pinpoint the exact origin.
Without more information it's hard to know for sure. One way this could happen is if you end up redefining a type in FSI without redefining some things that depend on it. Then those things expect the old version of the type, but you end up creating instances of the new version, which are not compatible. For instance, given this code:
type MyType<'a>() = class end
let myFun (_:MyType<int>) = 0
let result = myFun (MyType())
If I send the first two lines to FSI, then the first line again by itself, and then the third line, I get something similar to your error message. The solution is to re-evaluate all dependent definitions.
I'm trying to make an example I've found on the net work. It's a 3D fractal in F#. Here it is: http://tomasp.net/blog/infinite-cheese.aspx. The source code is available for download at the end of the article. The article and the sample were written in 2007, so I think the code is just slightly obsolete. There is one block of code that causes error and the code won't compile:
// Returns a cube with filtered sides
let private get_cube(incl_sides) =
[ for (side,trigs) in cube
when Set.mem side incl_sides
->> trigs ]
The when keyword is underlined, and the error message goes as follows:
Unexpected keyword 'when' in expression. Expected '->' or other token.
I can't figure out what's wrong with this. In an attempt to understand the code better, I searched the langauge specs. As far as I know, there is nothing about the Set.mem function or the ->> operator. Do you have any idea what could be wrong?
Try
[for (side, trigs) in cube do
if Set.contains side incl_sides then
yield! trigs]
The language has undergone a lot of changes since that code was written. In particular, the ->> operator has been replaced by yield!, Set.mem has been renamed to the more descriptive Set.contains, and comprehensions now use if ... then instead of when.
Yes, the version of the source code that is linked from the blog post is a bit old. You can find the latest (updated) version in the F# samples project on CodePlex. I think there may be some other changes, so it is best to get the version from CodePlex. (It includes FractalSimple.fs which is simpler version and Fractal.fs which also removes cube sides that are not visible).
The project contains standard Visual Studio 2008/2010 .fsproj project. The original version on the blog was written using F# CTP (from VS 2005 times) which had a completely different Visual Studio integration and used an obsolete .fsharpp project format (before MSBUILD format existed).
The when and ->> constructs have been used as a lightweight syntax for writing queries, but are now deprecated, to keep the syntax inside comprehensions consistent with the rest of the language. As kvb points out, you can use ordinary if .. then and the only non-standard thing is yield!, which means return all elements of the given sequence.
I am using Delphi 2007 with all patches and updates.
I have a file which is used by two different projects. In that file is a procedure, which I will simplify as follows:
procedure MyProcedure;
const
UniqueValue: integer = 0;
begin
//some code
Inc(UniqueValue);
//some more code
end;
The Inc() command should fail, because you cannot assign to a constant. In one project, I get an error to that effect (I'll call that project "Accurate"). In the other project, I don't get any errors (I'll call it "Bogus"). I also don't get any warnings. I can't figure out why the compiler lets this incorrect code through.
Here's what I've tried in project Bogus:
1 - Introduce an obvious error, like typing "slkdjflskdjf" in the middle of a line
Result: I get an error,which proves that it is really trying to compile this file.
2 - Delete the .DCU, and rebuild the project
Result: The .DCU is re-generated, again proving that the project is truly compiling this erroneous code.
Does anyone have thoughts on why this behavior would occur? And more specifically, why it would occur in one project but not another? Is there some obscure compiler option to permit assigning to constants?
One final note: Both projects are converted from Delphi 5. Under Delphi 5 with similar code, they both compile fine.
Edit: Thanks for all your help. After changing the assignable typed constants directive, I can get consistent behavior across both projects. I learned something new today...
There is an option for this called "Assignable typed constants" in Compiler Options. It can also be enabled with "{$J+}" in your code.
Could it be that those projects differ in the setting of the $J compiler directive?
I'd suggest to check the Project Options, section Compiler and see if you can spot any differences. Maybe you have option Assignable typed constants enabled in the Bogus project.
As others have said it's almost certainly the {$J+} directive.
If you have a diff tool you can compare the project files to see how they differ - they're just text files - to solve similar problems in the future.