Re: [Gambas-user] isNull()
Le 25 novembre 2010 00:31, Benoît Minisini gam...@users.sourceforge.net a écrit : I use IsNull extensively, is that going to be removed? richard No. I use it extensively too. Here is the result of my thought: - You can know the datatype of a variant with the TypeOf() function. You don't have to use the current Is() functions. - But you often need to know if a string can be converted to a number, an integer, a float, a date. - You normally want to know that for localized strings get from the outside (i.e. the user). For non-localized strings, they are intern to your program, so you should know what you are doing. So: IsNull(x) - kept its behaviour. IsInteger(x) - If Val(x) returns an integer IsFloat(x) - If Val(x) returns a float IsDate(x) - If Val(x) returns a date hum ... isBinary ? but how do you test if it's not ? i imagine it is taht : Function isFloat(Value as variant) as Float dim fValue as Float fValue = Val(Value) if not error then return fValue end but in the other side i need to test it :/ again if isFoat(Value) then print isFloat(Value) in fact there is not fabulous soluce as we need two thing, known if a convertion is possible with this datatype and then get the value. the only one soluce i see is the C way... with a byref value Function isFloat(Value as variant, Byref Ret as Float) as Boolean dim fValue as Float fValue = Val(Value) if not error then Ret = fValue Return True endif return end Dim fRet as Float If IsFloat(Value, ByRef fRet) then Print fRet They should be enough. But I could add: IsLong(x) - If Val(x) returns a Long IsSingle(x) - If Single(x) returns a Single. Regards, -- Benoît Minisini -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user -- Fabien Bodard -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
Re: [Gambas-user] isNull()
On Thu, 25 Nov 2010 10:01:42 am Benoît Minisini wrote: I use IsNull extensively, is that going to be removed? richard No. I use it extensively too. Here is the result of my thought: - You can know the datatype of a variant with the TypeOf() function. You don't have to use the current Is() functions. - But you often need to know if a string can be converted to a number, an integer, a float, a date. - You normally want to know that for localized strings get from the outside (i.e. the user). For non-localized strings, they are intern to your program, so you should know what you are doing. So: IsNull(x) - kept its behaviour. IsInteger(x) - If Val(x) returns an integer IsFloat(x) - If Val(x) returns a float IsDate(x) - If Val(x) returns a date They should be enough. But I could add: IsLong(x) - If Val(x) returns a Long IsSingle(x) - If Single(x) returns a Single. Regards, Benoît, I would like to see the generic IsNumber retained. When dealing with external data sources, i.e. data from an external system source not a user the content of data fields in a database can vary widely over time. In different eras, a particular column may have it's type changed in the source database system but the existent data remains undisturbed. Although it sounds weird, we often see data columns on mainframe and even on some PC based rdbms that have gone from a text (or char or varchar) to a numeric type, to a different numeric type and so forth. In these database systems, any new inserts or updates will conform to the current type definition. However, existing data is left as is. So if booktype was originally char(1), then became charvar then became a specific structured datatype (for example, some of the custom types provided for in postgresql), we still see instances of, say A being returned by the dbms for booktype. (The way we handle this is by way of our own postgresql front end database that accesses the remote dbms and returns text fields for any and all columns that contain suspect data types.) In the main, I don't care if the field contains an integer or a float (or a long or single etc) just that it contains a number and not any non-numeric data. I will worry about the representation after I have determined that it is a number. I realise that this is a fairly arcane use of gambas, but the speed that we can develop (and run) filters based on this approach is why I chose gambas in the first place. As I said, we use a 80-20 rule to get to the core issue of the data as soon as possible. The parsing filters get more and more complex for each 20% left over. So the ability to recognise generic datatypes in string values, is it a number, good, then return true else start looking for other clues as to what it is supposed to represent ... does it look like it might be a date? If so then try to decipher the date structure, else does it look like a known construct (i.e IF wkstr LIKE *(*%)* then ...) etc etc. Oh, and by the way, I too use IsNull extensively, specifically to provide lazy loads of subordinate persisted objects, usually collections, whose content is not required unless specifically accessed. For example, a Book object may have a property which is an Author object. When the persisted book object is loaded from the database, the author object is not loaded until the program actually accesses the book.author property, viz PRIVATE FUNCTION MyAuthor() as Author if IsNull($myAuthor) $myAuthor=NEW Author $myAuthor.LoadDB(ME.AuthorName) endif RETURN $myAuthor END (obviously simplified to exclude error checking). -- best regards Bruce Bruen -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
Re: [Gambas-user] isNull()
On Thu, 25 Nov 2010 10:01:42 am Benoît Minisini wrote: I use IsNull extensively, is that going to be removed? richard No. I use it extensively too. Here is the result of my thought: - You can know the datatype of a variant with the TypeOf() function. You don't have to use the current Is() functions. - But you often need to know if a string can be converted to a number, an integer, a float, a date. - You normally want to know that for localized strings get from the outside (i.e. the user). For non-localized strings, they are intern to your program, so you should know what you are doing. So: IsNull(x) - kept its behaviour. IsInteger(x) - If Val(x) returns an integer IsFloat(x) - If Val(x) returns a float IsDate(x) - If Val(x) returns a date They should be enough. But I could add: IsLong(x) - If Val(x) returns a Long IsSingle(x) - If Single(x) returns a Single. Regards, Benoît, I would like to see the generic IsNumber retained. When dealing with external data sources, i.e. data from an external system source not a user the content of data fields in a database can vary widely over time. In different eras, a particular column may have it's type changed in the source database system but the existent data remains undisturbed. Although it sounds weird, we often see data columns on mainframe and even on some PC based rdbms that have gone from a text (or char or varchar) to a numeric type, to a different numeric type and so forth. In these database systems, any new inserts or updates will conform to the current type definition. However, existing data is left as is. So if booktype was originally char(1), then became charvar then became a specific structured datatype (for example, some of the custom types provided for in postgresql), we still see instances of, say A being returned by the dbms for booktype. (The way we handle this is by way of our own postgresql front end database that accesses the remote dbms and returns text fields for any and all columns that contain suspect data types.) In the main, I don't care if the field contains an integer or a float (or a long or single etc) just that it contains a number and not any non-numeric data. I will worry about the representation after I have determined that it is a number. I realise that this is a fairly arcane use of gambas, but the speed that we can develop (and run) filters based on this approach is why I chose gambas in the first place. As I said, we use a 80-20 rule to get to the core issue of the data as soon as possible. The parsing filters get more and more complex for each 20% left over. So the ability to recognise generic datatypes in string values, is it a number, good, then return true else start looking for other clues as to what it is supposed to represent ... does it look like it might be a date? If so then try to decipher the date structure, else does it look like a known construct (i.e IF wkstr LIKE *(*%)* then ...) etc etc. Oh, and by the way, I too use IsNull extensively, specifically to provide lazy loads of subordinate persisted objects, usually collections, whose content is not required unless specifically accessed. For example, a Book object may have a property which is an Author object. When the persisted book object is loaded from the database, the author object is not loaded until the program actually accesses the book.author property, viz PRIVATE FUNCTION MyAuthor() as Author if IsNull($myAuthor) $myAuthor=NEW Author $myAuthor.LoadDB(ME.AuthorName) endif RETURN $myAuthor END (obviously simplified to exclude error checking). You must check the datatype of a column by using Result.Fields[xxx].Type, not by using Is() on the value. Or if really you don't want, use TypeOf(). Anyway, in my list, IsFloat() does what you want IsNumber() to do, as there is no number higher than Float in the Gambas number hierarchy. Regards, -- Benoît Minisini -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
[Gambas-user] isNull()
I use IsNull extensively, is that going to be removed? richard -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
