Changes and Enhancements to the SAS Component Language (SCL)

Transcription

1 Changes and Enhancements to the SAS Component Language (SCL) Carl LaChapelle

2 Introduction SCL has undergone many changes over the years. None have been more dramatic than the changes made between V6 and V8.

3 Topics to be Covered! Dot Notation! SCOM! Declare Statement! List Syntax! Error Handling! Method Improvements! Array Enhancements! Question & Answers

4 Dot Notation! Clear and consistent syntax for accessing an object s methods and attributes! First-level qualifier is always the name of the object! Second-level qualifier is attribute or method name

5 Dot Notation! Don t have to remember which method to call(send, notify)! Less prone to syntax errors! Object names can now be up to 32 characters

6 Dot Notation returnvalue = object.method(); object.attribute = value; value = object.attribute;

7 Before Dot Notation list = makelist(); call notify( graph, _get_region_,list); title = getnitemc( list, border_title ); style = getnitemc( list, border_style ); color = getnitemc( list, border_color ); rc = dellist(); put title= style= color=;

8 With Dot Notation put graph.bordertitle= graph.borderstyle= graph.bordercolor=;

9 SCOM! SAS Component Object Model! An object with specific properties:! Attributes! Methods! Events! Event handlers! Interfaces

10 SCOM! A legacy(v6) object s name refers to the object s value.! A component s name refers to the component s object ID.

11 SCOM! You can use dot notation with legacy objects! Select Use object name as ID in SCL checkbox in the property sheet! Set value of objectnameusage attribute to ID in the class editor! Programmatically declare object of correct type

12 SCOM! For more details on SCOM, refer to the SUGI24 paper titled: SAS Component Object Model (SCOM) in Version 7 of SAS/AF Software

13 Declare Statement! New DECLARE(or DCL) statement! Use to declare all variables! Valid variable types are:! Character! Numeric! List! Object! Array

14 Declaring Variables! The DCL statement uses a set of keywords to recognize type declarations! NUM! CHAR! LIST! OBJECT! 4-level class name

15 Declaring Variables! Blanks are used to separate variables of the same type, commas separate variables of disparate types dcl char lastname = Smith ; dcl list mylist; dcl num age weight, char(20) lastname;

16 Declaring Objects! There are two ways to declare objects! Declare it as a generic object declare object myobject;! Specify the class name that the object represents declare sashelp.fsp.image.class imgobj;

17 Declaring Variables dcl char(10) name colors, num cost; dcl num age(3) = (21, 40, 65); dcl sashelp.classes.datasetlist_c myobj = instance(loadclass( sashelp )); dcl list mylist = makelist(); dcl list colorlist = { red, green, blue };

18 Declaring Objects! When instantiating objects or creating lists using the DCL statement, it is your responsibility to perform the appropriate cleanup(dellist, _term)

19 List Syntax! Can be used anywhere in your SCL! The rules are:! Use { to begin the definition of a list! Use } to end the definition of a list! Use name= to name an item! Separate items in the list with commas! Embed sublists by using additional { }

20 List Syntax colorlist = { red, green, blue }; infolist = { firstname = Carl, lastname = LaChapelle }; infolist = { employee = { firstname = Carl, lastname = LaChapelle }, company = SAS };

21 List Syntax! Cannot use variable substitution or string concatenation when defining a list item! Remember to call DELLIST!

22 List Functions! comparelist! getitemo! getnitemo! inserto! searcho! setitemo! setnitemo

23 Error Handling! It s now possible to trap program halts, and control program execution! Use program halt class to do this (sashelp.classes.programhalt.class)! You can determine what has happened, and conditionally allow the execution to continue

24 Error Handling! Override methods in programhalt class to trap specific errors _onattributeerror _ongeneric _ongenericmath _onoverflow _onunderflow _onzerodivide

25 Error Handling! The attributes of the programhalt class give you information about the halt these attributes are read-only! dump(list) A list containing the actual program halt! entry(char) The four-level name of the entry where the program halt occurred

26 Error Handling! Keyword(char) The name of the method or function in which the program halt occurred! keywordtype(char) Indicates what the value of the keyword attribute represents! linenumber(num) The line number in the entry where the halt occurred

27 Error Handling! traceback(list) A list which contains the SCL traceback! type(char) Indicates the type of program halt that has occurred(generic, genericmath, overflow, underflow, zerodivide, attributerror)

28 Error Handling! To control execution you can set the stopexecution attribute! The default value is Yes, which causes execution to terminate! If set to No, execution will continue at the instruction following the one that caused the program halt

29 Error Handling! A more limited alternative is to use the nohaltondotattribute option on the CONTROL statement! This only affects program halts that are due to setting attribute values! You don t know that a program halt has occurred

30 What s New With Methods?! New naming conventions! Method signatures! Method overloading

31 Method Naming Conventions! Fewer underscores! V6 _set_text_color_! V8 _settextcolor! For compatibility purposes both names are equivalent! Mixed casing for presentation, but not for comparison! You can create methods with a leading underscore

32 Method Signatures! A method signature is a set of parameters that uniquely identifies a method to the SCL compiler! Can improve the performance of your application! Allows you to have overloaded methods

33 Method Signatures! A method signature is a set of parameters that uniquely identifies a method to the SCL compiler! Can improve the performance of you application! Allows you to have overloaded methods

34 Method Signatures! The signature is usually represented by the sigstring! The format is (parms)returnval! (None) is not the same as ()V

35 Method Signatures! The method signatures are used by the compiler to detect the following errors! The method does not exist in the class! The incorrect number or type of arguments are being passed to the method! By validating at compile time, run time checking is reduced or eliminated

36 Method Signatures! The compile time validation and run time performance gains are subject to the following rules! Only supported through dot notation, or USECLASS, and not call SEND or NOTIFY! Method cannot have a signature of (None)

37 Method Overloading! Method overloading is when a component has more than one method with the same name, but different signatures dcl char(10) color, num r g b; myobj.setcolor( color ); /* (C)V */ myobj.setcolor( r, g, b ); /* (NNN)V */

38 Method Overloading! Rules for overloading methods! A method with a signature of (None) cannot be overloaded! The signatures cannot differ only by return type M1(NC)V M1(NN)N is valid M1(NC)V M1(NC)N is not valid

39 Declaring MethodsMethod Scope! You can specify additional information when declaring a method! Define the methods scope! PUBLIC(default), PRIVATE, PROTECTED! Define the role of each argument! INPUT, OUTPUT, UPDATE(default)! Specify the type of the return value

40 Method Scope! If Scope='Public', then any class and frame SCL can call the method. The method does appear in the component's Properties window at build time. This is the default method scope.

41 Method Scope! If Scope='Protected', then only the class and any subclasses can call the method. The method does not appear in the component's Properties window at build time, nor can you access the method via frame SCL.

42 Method Scope! If Scope='Private', then only the class itself can call the method. The method does not appear in the component's Properties window at build time, nor can you access the method via frame SCL.

43 Declaring Methods! The defaults are the same as V6! As with V6, only an argument s name and type are required

44 USECLASS! Allows the compiler to validate the SCL code against the information in the class entry! Improved run time performance due to validation occurring at compile time instead of at run time! Syntax shortcuts can be used (no more _self_)

45 USECLASS Syntax USECLASS four-level-class-name < one or more method blocks > ENDUSECLASS; Where four-level-name is the name of the class entry that owns the methods you are implementing

46 Class Syntax! You can now create and manage a class in SCL!! Useful when making lengthy and repetitive changes! Allows you to diff two classes

47 Class Syntax <ABSTRACT> CLASS class-name <EXTENDS parent-class-name> <SUPPORTED supported-interface> <REQUIRED required-interface> </ (class-metadata)> <(attribute-statements)> <(method-declaration-statements)> <(method-implementation-blocks)> <(event-declaration-statements)> <(eventhandler-declaration-statements)> ENDCLASS;

48 Class Syntax! To create an SCL entry from a class! Use File->Save As in class editor! Call createscl function

49 Dynamic Arrays! Do not specify the size when you declare them dcl num depts[ 5 ] employees[ * ];! Allocate and resize them as needed in your SCL program! Must allocate the array before elements can be referenced or assigned

50 Array Enhancements! Can now be used in assignment statements! When passed as a parameter they are treated as a reference! Can be used as a return argument for a method! Both static and dynamic arrays can be used as attributes in a class

51 Array Functions! makearray! redim! copyarray! comparearray! delarray! redimopt(8.1)

52 New Host Dialogs! The following functions now display host specific dialog windows! messagebox! openentrydialog! saveentrydialog! opensasfiledialog! savesasfiledialog

53 Conclusion We have made a significant number of enhancements to SCL in V8! A simpler coding style! Improved OO features! Improved validation, and performance However, these enhancements were not made at the expense of your existing applications

54 Questions?

55 Acknowledgements! Tammy did a tremendous amount of work on this presentation! Thank you for attending!

56 About the Speaker Speaker Location of company Carl LaChapelle Director, Display Products SAS Institute Inc. SAS Campus Dr. Cary, NC, Telephone Fax (919) (919)