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This article mainly explains "how to use Code Inspector in ABAP". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor learn how to use Code Inspector in ABAP.

In the check variant (Check Variant) of ABAP Code Inspector, we have the flexibility to choose which type of scan action to perform on the ABAP code according to our own needs.

The following figure is an example of a "Table Names from SELECT Statements" scan of all places in the ABAP code that have read and write access to the database table. For the specific behavior of the scan, you can click on the blue background and white exclamation mark image to get help documentation. The option checked in the example below means to check whether the Technical Settings in the ABAP field of the accessed database table is correctly maintained, such as whether the cache type of the table is set correctly.

Performance Check

Select-Statement can be transformed. X% of fields used-check the utilization of inner table fields

Suppose we use SELECT * to read data from a table to the table in ABAP, and then only A fields are used in the subsequent code, while the table read has a total of B fields in SE11. The smaller the result of A divided by B, the lower the utilization of the fields in the read inner table.

In other words, you might want to consider replacing SELECT * with only the fields that SELECT really needs? You only need to maintain a minimum threshold in the above settings, and when Code Inspector scans the code, it will report an error if it detects that the utilization rate is lower than the maintenance threshold. 20 in the picture above means 20%.

Search DB Operations in loops across modularization units

When Jerry first joined SAP in 2007 and started learning ABAP programming, my predecessors warned me not to use select statements in LOOP, which would greatly affect the performance of the code.

The image above is an example scanned through Code Inspector, using SELECT to read the database table CRMD_DPP_HI_BLCK in a double LOOP loop.

Nested Loops-Detection of nested loops

Although when the number of loops nested in the application code is small, it does not have much effect on the absolute time of the code to run-writing code with at least exponential time complexity is not a good programming habit in any context.

This setting can help us quickly find all the nested loops.

Copy current table row for LOOP AT

Find all the LOOP AT... INTO, in theory, all of these places can use LOOP AT. REFERENCE INTO or ASSIGNING replacement. When there are a lot of row structure fields in the inner table, you can get some performance improvement by using the latter two ways.

Low-Perform. Parameter Transfers-detects the use of "Pass by Value" in all parameter passes

Jerry followed a lot of technical official accounts and found that the discrimination between "passing reference" and "passing value" of parameter transmission is still one of the interview questions for many Internet companies.

This option allows you to specify the type of parameter for which the scan is passed:

In ABAP, using reference transfer to pass parameters in theory, the performance is always better than value transfer, the specific performance will be improved, depending on the specific type of parameters passed, can not be generalized.

Security Check-Dynamic and Client-Specific accesses in SELECT-Detection of dynamic SQL statements

Dynamic SQL that matches the following paradigm is scanned out:

Dynamic table accesses: SELECT * FROM (dbtab) WHERE …

Dynamic WHERE conditions: SELECT * FROM dbtab WHERE (where_cond)

Accesses to certain tables: SELECT * FROM dbtab WHERE …

Client-specific accesses: SELECT * FROM dbtab FROM WA … CLIENT SPECIFIED...

This option does not prohibit you from using dynamic SQL statements-- in fact, there are a large number of examples of the use of dynamic SQL statements in the persistence layer of SAP applications-- but reminds you of the precautions for SQL injection: once scanned, if user input is involved in the splicing of these dynamic SQL statements, don't forget to see if the context uses CL_ABAP_DYN_PRG to process user input.

Search for APPEND and INSERT... INDEX in SORTED Tables

Detect all places where the APPEND operation is applied on the ordered inner table. With this scanning option, you can help you avoid this type of run-time error in line 13 below.

Detection of system variable sy-subrc after Check of SY-SUBRC Handing-ABAP keyword call

Jerry still remembers clearly that when he took the graduate course "Advanced programming in the UNIX Environment" more than a decade ago, the teacher repeatedly stressed that the return value must be checked and error handling should be carried out after making the system call. In Jerry's view, error detection and handling are the basic qualities that every programmer should have.

In ABAP, it means that every time you call the keyword of ABAP to complete an operation, you must check the value of sy-subrc to confirm whether the operation is successful.

Of course, depending on the actual situation of the project, you can tell Code Inspector to check only certain types of ABAP keyword calls. For example, the figure above only checks whether sy-subrc is checked after the READ TABLE keyword is called.

Missing table content check before calling SELECT... FOR ALL ENTRIES IN

Before using FOR ALL ENTRIES IN, you must check that the inner table itab is empty. This option scans out code that is not written according to this specification.

Programming Conventions-Naming conventions

Set up agreed naming conventions for different types of variables in ABAP in this interface, and then Code Inspector can scan all the places in the code that violate these naming conventions.

Metrics and Statistics

The settings under this check category are some interesting statistics.

Let's give an example. The red area below is set, meaning that if there are more than 150 lines of executable statements in the method of a class, Code Inspector reports a warning message. This is to prevent people from writing an overly lengthy method.

The blue area is set to report a warning message if the corresponding comment for every 100 lines of executable code is less than 10 lines. These thresholds can be modified or closed according to the actual situation.

FAN-OUT Structural Metrics-Statistics the fan-out value of a method

The fan-in and fan-out values of the method are often mentioned in the context of modular programming, which are not pioneered in the programming world, but from logic circuit design in the semiconductor industry:

The fan-out coefficient of the logic gate defines the maximum amount of digital signal input that the gate can drive, while the fan-out value of a code module represents the number of modules directly under it.

This option allows you to count the fan out coefficient of your method. The fan-out coefficient is too small, which means that the method basically does not call other lower-level functions, which has two possibilities:

The logic of the method itself is very simple, with only two or three lines of code, such as the setter/getter method of the class

The modularization of this method is not well done, and there is room for optimization, such as some statements written directly in the method, which can be refined into lower-level functions and called within the method.

Comment Language Metrics

This option allows you to count the German annotated functions that appear in the code.

Jerry doesn't quite understand the usefulness of this option for non-German ABAP developers to complain about?

OO Size Metrics

This option is also designed to prevent you from inadvertently creating a monster class (monster class): once the properties of the class you care about exceed the set threshold, such as the members of the class, the public / private methods of the class, and other concerns exceed the value set in the option, Code Inspector will alarm.

Program Complexity Test-cyclomatic complexity-A sharp tool for testing code loop complexity (cyclomatic complexity)

This is another powerful tool that can help you write Clean ABAP code.

What is the loop complexity of the code?

According to the Wikipedia definition, we draw the execution flow of a piece of code as a directed acyclic graph, and then the ring complexity can be calculated by the following formula:

Https://en.wikipedia.org/wiki/Cyclomatic_complexity

Ring complexity = number of edges of a graph-number of nodes of a graph + 2

In fact, this is the Euler theorem that we learned in our graduate course "Graph Theory".

Look at the following example:

The above 8 lines of ABAP code, the ring complexity is 3, how is it calculated?

First draw the corresponding directed acyclic graph:

The number of sides of this picture is 3, that is, the three thick lines of black, red and green in the picture.

The number of vertices in this picture is 2, as shown in the blue illustrations of the two diamonds in the figure.

Finally, the complexity of the loop is 3-2 + 2 = 3.

Statistics show that there is a strong positive correlation between the high loop complexity and the high failure rate of the code, which is not difficult to understand. The higher the complexity of the code, the more logic such as IF-ELSE,SWITCH is nested in it. Whether the original developer of the code or the maintenance staff who took over later, you will feel dizzy when reading it.

Therefore, you can use this scanning option of ABAP Code Inspector to monitor the complexity of your code at any time.

Search DB Operations

List all the SQL operation keywords that appear in the code that you are concerned about.

Search ABAP Statement Patterns

This option is also useful to scan ABAP code based on regular expressions you specify.

For example, if you want to find out all the places in the code where READ TABLE XXX WITH KEY X = X appears, just fill in the corresponding regular expression in the input box of the figure above, that is, use * to represent any string:

READ TABLE * WITH KEY * = *

Then ABAP Code Inspector scans the code as we expect it to do:

The ABAP report RS_ABAP_SOURCE_SCAN can also achieve exactly the same functionality:

At this point, I believe you have a deeper understanding of "how to use Code Inspector in ABAP". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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