diff --git a/01_Internal_Tables.md b/01_Internal_Tables.md
index 667c7a0..1d9f7d2 100644
--- a/01_Internal_Tables.md
+++ b/01_Internal_Tables.md
@@ -470,7 +470,7 @@ APPEND INITIAL LINE TO itab.
INSERT INITIAL LINE INTO TABLE itab.
```
-**Adding a line and assignin the added line to a field symbol or data reference variable**.
+**Adding a line and assigning the added line to a field symbol or data reference variable**.
```abap
"When inserting single lines, you can specify the optional additions
"ASSIGNING and REFERENCE INTO. If the insertion is successful, the
diff --git a/04_ABAP_Object_Orientation.md b/04_ABAP_Object_Orientation.md
index 804b9a7..54a5e73 100644
--- a/04_ABAP_Object_Orientation.md
+++ b/04_ABAP_Object_Orientation.md
@@ -14,13 +14,20 @@
- [Creating the Visibility Sections](#creating-the-visibility-sections)
- [Defining Components](#defining-components)
- [Working with Objects and Components](#working-with-objects-and-components)
+ - [Declaring Reference Variables](#declaring-reference-variables)
+ - [Creating Objects](#creating-objects)
+ - [Assigning Reference Variables](#assigning-reference-variables)
+ - [Accessing Attributes](#accessing-attributes)
+ - [Calling Methods](#calling-methods)
+ - [Method Chaining](#method-chaining)
+ - [Self-Reference me](#self-reference-me)
- [Notes on Inheritance](#notes-on-inheritance)
- [Notes on Polymorphism and Casting](#notes-on-polymorphism-and-casting)
- [Notes on Interfaces](#notes-on-interfaces)
- - [Additional Notes](#additional-notes)
+ - [Excursions](#excursions)
- [Friendship](#friendship)
- [Events](#events)
- - [Excursion: Factory Methods and Singletons as Design Patterns](#excursion-factory-methods-and-singletons-as-design-patterns)
+ - [Factory Methods and Singletons as Design Patterns](#factory-methods-and-singletons-as-design-patterns)
- [More Information](#more-information)
- [Executable Example](#executable-example)
@@ -293,7 +300,7 @@ ENDCLASS.
(also known as
[signature](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensignature_glosry.htm "Glossary Entry"))
with which methods can get values to work with when being called and pass values
- back to the caller.
+ back to the caller (see the notes on formal and actual parameters below).
- [Static
methods](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstatic_method_glosry.htm "Glossary Entry")
can only access static attributes of a class and trigger static
@@ -329,7 +336,10 @@ In the simplest form, methods can have no parameter at all. Apart from that, met
[generic](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abengeneric_data_type_glosry.htm "Glossary Entry")
or
[complete](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abencomplete_data_type_glosry.htm "Glossary Entry")
- type.
+ type. Examples:
+> - `fp` is the formal parameter that has a complete type: `... meth IMPORTING fp TYPE string ...`
+> - `gen` is the formal parameter that has a generic type: `... meth IMPORTING gen TYPE any ...`
+> - Find more information about generic types also in the [Data Types and Data Objects](16_Data_Types_and_Objects.md#generic-types) cheat sheet.
> - This formal parameter includes the specification of how the
value passing should happen. Parameters can be [passed by
reference](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenpass_by_reference_glosry.htm "Glossary Entry")
@@ -420,11 +430,18 @@ CLASS local_class DEFINITION.
stat_meth3 IMPORTING VALUE(m) TYPE i, "pass by value
stat_meth4 IMPORTING REFERENCE(n) TYPE i, "pass by reference
stat_meth5 IMPORTING o TYPE i, "same as n; the specification of REFERENCE(...) is optional
- stat_meth6 RETURNING VALUE(p) TYPE, "pass by value once more (note: it's the only option for returning parameters)
+ stat_meth6 RETURNING VALUE(p) TYPE i, "pass by value once more (note: it's the only option for returning parameters)
"OPTIONAL/DEFAULT additions
stat_meth7 IMPORTING q TYPE i DEFAULT 123
- r TYPE i OPTIONAL.
+ r TYPE i OPTIONAL,
+
+ "The examples above use a complete type for
+ "the parameter specification. Generic types
+ "are possible.
+ stat_meth8 IMPORTING s TYPE any "Any data type
+ t TYPE any table "Any internal table type
+ u TYPE clike. "Character-like types (c, n, string, d, t and character-like flat structures)
ENDCLASS.
@@ -441,7 +458,7 @@ ENDCLASS.
## Working with Objects and Components
-**Declaring reference variables**:
+### Declaring Reference Variables
- To create an object, a [reference variable](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenreference_variable_glosry.htm "Glossary Entry")
must be declared.
- Such an [object reference
@@ -455,7 +472,9 @@ DATA: ref1 TYPE REF TO local_class,
ref3 LIKE ref1.
```
-**Creating objects**:
+
+
+### Creating Objects
- Using the instance operator
[`NEW`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconstructor_expression_new.htm),
@@ -494,7 +513,10 @@ DATA(ref2) = NEW some_class( ). "Reference variable declared inline, explic
"CREATE OBJECT ref4 TYPE some_class. "Corresponds to the result of the expression above
```
-**Assigning reference variables**: To assign or copy
+
+
+### Assigning Reference Variables
+To assign or copy
reference variables, use the [assignment
operator](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenassignment_operator_glosry.htm "Glossary Entry")
`=`. In the example below, both object reference variables have the same
@@ -510,6 +532,8 @@ ref1 = NEW #( ).
ref2 = ref1.
```
+More examples for dealing with object reference variables:
+
**Overwriting reference variables**: An [object
reference](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenobject_reference_glosry.htm "Glossary Entry")
is overwritten when a new object is created with a reference variable
@@ -545,7 +569,9 @@ CLEAR ref.
> Objects use up space in the memory and should therefore be
cleared if they are no longer needed. However, the [garbage collector](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abengarbage_collector_glosry.htm "Glossary Entry") is called periodically and automatically by the [ABAP runtime framework](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenabap_runtime_frmwk_glosry.htm "Glossary Entry") and clears all objects without any reference.
-**Accessing attributes**:
+
+
+### Accessing Attributes
- Instance attributes: Accessed using
the [object component selector](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenobject_component_select_glosry.htm "Glossary Entry")
`->` via a reference variable.
@@ -572,7 +598,9 @@ DATA dobj1 TYPE some_class=>some_type.
DATA dobj2 LIKE some_class=>some_static_attribute.
```
-**Calling methods**:
+
+
+### Calling Methods
- Similar to accessing attributes, instance
methods are called using `->` via a reference variable.
- Static
@@ -580,11 +608,8 @@ methods are called using `=>` via the class name. When used
within the class in which it is declared, the static method can also be
called without `class_name=>...`.
- When methods are called, the (non-optional) parameters must be specified within parentheses.
-- You might also stumble on method
-calls with [`CALL METHOD`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapcall_method_static.htm)
-statements in older programs. It should no longer be used, however, `CALL METHOD` statements are the
-only option in the context of dynamic programming.
-
+- You might also stumble on method calls with [`CALL METHOD`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapcall_method_static.htm)
+statements. These statements should no longer be used. Note that `CALL METHOD` statements are the only option in the context of [dynamic programming](06_Dynamic_Programming.md). Therefore, `CALL METHOD` statements should be reserved for dynamic method calls.
Examples for instance method calls and static method calls:
@@ -642,13 +667,13 @@ class_name=>meth( CHANGING g = h ).
"Calling (static) methods having a returning parameter.
"Basically, they do the same as methods with exporting parameters
-"but they are way more versatile and you save lines of code.
+"but they are way more versatile, and you can save lines of code.
"They do not need temporary variables.
"In the example, the return value is stored in a variable declared inline.
"i and k are importing parameters
-DATA(result) = class_name=>meth( i = j k = l )
+DATA(result) = class_name=>meth( i = j k = l ).
"They can be used with other statements, e. g. logical expressions.
"In the example below, the assumption is that the returning parameter is of type i.
@@ -659,17 +684,78 @@ ENDIF.
"They enable method chaining.
"The example shows a method to create random integer values.
"The methods have a returning parameter.
-
DATA(random_no) = cl_abap_random_int=>create( )->get_next( ).
-"Receiving parameter: Available in methods defined with a returning parameter;
+"RECEIVING parameter: Available in methods defined with a returning parameter;
"used in standalone method calls only.
"In the snippet, m is the returning parameter; n stores the result.
-
class_name=>meth( EXPORTING i = j k = l RECEIVING m = DATA(n) ).
```
-**Self-Reference me**
+
+
+### Method Chaining
+
+As shown in the previous example, method chaining is possible for functional method calls (i.e. methods that have exactly one return value declared with `RETURNING`) at appropriate read positions. In this case, the method's return value is used as an ABAP operand.
+A chained method call can consist of multipled functional methods that are linked using component selectors `->`. The return values of each method are references to the next method.
+
+```abap
+"The following example demonstrates method chaining
+"The following class creates random integers. Find more information in the
+"class documentation.
+"Both methods have returning parameters specified.
+DATA(some_int1) = cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
+ min = 1
+ max = 10 )->get_next( ).
+
+"Getting to the result as above - not using method chaining and inline declarations.
+DATA some_int2 TYPE i.
+DATA dref TYPE REF TO cl_abap_random_int.
+
+dref = cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
+ min = 1
+ max = 10 ).
+
+some_int2 = dref->get_next( ).
+
+"Using the RECEIVING parameter in a standalone method call
+DATA some_int3 TYPE i.
+dref->get_next( RECEIVING value = some_int3 ).
+
+"IF statement that uses the return value in a read position
+IF cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
+ min = 1
+ max = 10 )->get_next( ) < 5.
+ ... "The random number is lower than 5.
+ELSE.
+ ... "The random number is greater than 5.
+ENDIF.
+
+"Examples using classes of the XCO library (see more information in the
+"ABAP for Cloud Development and Misc ABAP Classes cheat sheets), in which
+"multiple chained method calls can be specified. Each of the methods
+"has a returning parameter specified.
+
+"In the following example, 1 hour is added to the current time.
+DATA(add1hour) = xco_cp=>sy->time( xco_cp_time=>time_zone->user )->add( iv_hour = 1 )->as( xco_cp_time=>format->iso_8601_extended )->value.
+
+"In the following example, a string is converted to xstring using a codepage
+DATA(xstr) = xco_cp=>string( `Some string` )->as_xstring( xco_cp_character=>code_page->utf_8 )->value.
+
+"In the following example, JSON data is created. First, a JSON data builder
+"is created. Then, using different methods, JSON data is added. Finally,
+"the JSON data is turned to a string.
+DATA(json) = xco_cp_json=>data->builder( )->begin_object(
+ )->add_member( 'CarrierId' )->add_string( 'DL'
+ )->add_member( 'ConnectionId' )->add_string( '1984'
+ )->add_member( 'CityFrom' )->add_string( 'San Francisco'
+ )->add_member( 'CityTo' )->add_string( 'New York'
+ )->end_object( )->get_data( )->to_string( ).
+```
+
+
+
+### Self-Reference me
When implementing instance methods, you can optionally make use of the implicitly available object reference variable [`me`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenme.htm) which is always available at runtime and points to the respective object itself. You can use it to refer to components of the instance of a particular class:
``` abap
@@ -1066,7 +1152,7 @@ i_ref = NEW class( ).
-### Excursion: Factory Methods and Singletons as Design Patterns
+### Factory Methods and Singletons as Design Patterns
In object-oriented programming, there a plenty of design patterns. Covering these ones here to get a rough idea: factory methods and singletons. Both are relevant if you want to restrict or control the instantiation of a class by external users of this class.
diff --git a/05_Constructor_Expressions.md b/05_Constructor_Expressions.md
index 665e4de..ea76929 100644
--- a/05_Constructor_Expressions.md
+++ b/05_Constructor_Expressions.md
@@ -1507,25 +1507,68 @@ DATA(it11) = VALUE itab_type( FOR wa IN itab USING KEY primary_key ( col1 = wa-c
*ccct 9 13
"---------- Conditional iterations ----------
+"Notes:
+"- When used with VALUE/NEW for internal tables: New table lines are created in
+" iteration steps and added to result
+"- When used with REDUCE (as shown below): Reduction result is created in iteration steps
+"- Regarding the THEN addition:
+" - Must be specified if the iteration variable specified after FOR is not a numeric data
+" type and not of type d/t
+" - If the iteration variable is a numeric type/type d or t, THEN is optional. If THEN
+" is not specified, the iteration variable is implicitly incremented by 1.
-"FOR ... WHILE ...
+"FOR ... WHILE ...
+"Implicit incrementing of the iteration variable
DATA(it12) = VALUE itab_type( FOR x = 1 WHILE x < 4
( col1 = x col2 = x + 1 col3 = x + 2 ) ).
*COL1 COL2 COL3
-* 1 2 3
-* 2 3 4
-* 3 4 5
+* 1 2 3
+* 2 3 4
+* 3 4 5
+
+"The following example corresponds to the previous one. Here, THEN
+"is explicitly specified.
+DATA(it13) = VALUE itab_type( FOR x = 1 THEN x + 1 WHILE x < 4
+ ( col1 = x col2 = x + 1 col3 = x + 2 ) ).
+
+"THEN explicitly specified
+DATA(it14) = VALUE itab_type( FOR x = 1 THEN x + 2 WHILE x < 8
+ ( col1 = x col2 = x + 1 col3 = x + 2 ) ).
+
+*COL1 COL2 COL3
+* 1 2 3
+* 3 4 5
+* 5 6 7
+* 7 8 9
+
+"THEN addition is required for non-numeric data types of the iteration
+"variable
+DATA(it15) = VALUE itab_type( FOR str = `x` THEN str && str WHILE strlen( str ) < 5
+ ( col1 = str col2 = strlen( str ) + 1 col3 = strlen( str ) + 2 ) ).
+
+*COL1 COL2 COL3
+*x 2 3
+*xx 3 4
+*xxxx 5 6
"FOR ... UNTIL ...
-"The THEN addition is also possible for ... WHILE ...
-DATA(it13) = VALUE itab_type( FOR y = 31 THEN y - 10 UNTIL y < 10
+DATA(it16) = VALUE itab_type( FOR y = 10 UNTIL y > 12
( col1 = y col2 = y + 1 col3 = y + 2 ) ).
*COL1 COL2 COL3
-* 31 32 33
-* 21 22 23
-* 11 12 13
+* 10 11 12
+* 11 12 13
+* 12 13 14
+
+"THEN explicitly specified
+DATA(it17) = VALUE itab_type( FOR y = 31 THEN y - 10 UNTIL y < 10
+ ( col1 = y col2 = y + 1 col3 = y + 2 ) ).
+
+*COL1 COL2 COL3
+* 31 32 33
+* 21 22 23
+* 11 12 13
```
@@ -1689,7 +1732,7 @@ DATA(it_val_2) = VALUE string_table(
*b: 7, 8 / 9, 10
*c: 11, 12
-"Constucting a result using REDUCE
+"Constructing a result using REDUCE
"The example is similar to the previous one by filling a string table.
"The example uses a group key expression specified after GROUP BY.
"In the group key expression, additional components of a structured
diff --git a/08_EML_ABAP_for_RAP.md b/08_EML_ABAP_for_RAP.md
index 4f2a8f1..1c67643 100644
--- a/08_EML_ABAP_for_RAP.md
+++ b/08_EML_ABAP_for_RAP.md
@@ -746,7 +746,7 @@ DATA rep TYPE RESPONSE FOR REPORTED entity.
### Components of BDEF Derived Types
Many of the BDEF derived types contain components of CDS entities like
-key and data fields that retain their original line type, for example, a
+key and data fields that retain their original data type, for example, a
messenger table typed with `TYPE TABLE FOR CREATE`. Certainly,
if an instance is to be created, key and field values of a RAP BO
instance are of relevance.
diff --git a/16_Data_Types_and_Objects.md b/16_Data_Types_and_Objects.md
index fb9d060..6bdca9c 100644
--- a/16_Data_Types_and_Objects.md
+++ b/16_Data_Types_and_Objects.md
@@ -336,7 +336,7 @@ FIELD-SYMBOLS:
TYPE xsequence, "Byte-like (x, xstring)
"Numeric types
- TYPE decfloat, "decfloat16, decfloat34)
+ TYPE decfloat, "decfloat16, decfloat34
TYPE numeric, "Numeric ((b, s), i, int8, p, decfloat16, decfloat34, f)
TYPE p, "Packed number (generic length and number of decimal places)
@@ -461,8 +461,11 @@ ASSIGN s-structure TO .
ASSIGN s-xl1 TO .
"ASSIGN s-tab_ha TO .
-ASSIGN s-oref TO