PyCharm features robust, fast, and flexible static code analysis. It detects compiler and runtime errors, suggests corrections and improvements before you even compile.
In this section:
- Code analysis basics
- Inspection scope
- Examples of code inspections
Code analysis basics
PyCharm performs code analysis by applying inspections to your code. Numerous code inspections exist for Python and for the other supported languages.
The inspections detect not only compiling errors, but also different code inefficiencies. Whenever you have some unreachable code, unused code, non-localized string, unresolved method, memory leaks or even spelling problems – you'll find it very quickly.
PyCharm's code analysis is flexibly configurable. You can enable/disable each code inspection and change its severity, create profiles with custom sets of inspections, apply inspections differently in different scopes , suppress inspections in specific pieces of code, and more.
The analysis can be performed in several ways:
- By default, PyCharm analyses all open files and highlights all detected code issues right in the editor. On the right side of the editor you can see the analysis status of the whole file – the icon in the top changes its color when a problem is detected.
- Alternatively, you can run code analysis in a bulk mode for the specified scope, which can be as large as the whole project.
- If necessary, you can apply a single code inspection in a specific scope.
For most of detected code issues, PyCharm provides quick fix suggestions. You can quickly review errors in a file by navigating from one highlighted line to another by pressing F2/⇧+F2.
When you inspect your code, you can tell PyCharm which types of problems you would like to search for and get reports about. Such configurations can be preserved as inspection profiles.
An inspection profile defines the types of problems to be sought for, i.e. which code inspections are enabled/disabled and the severity of these inspections. Profiles are configurable in the Inspections settings page.
To set the current inspection profile (the one that is used for the on-the-fly code analysis in the editor), simply select it in the Inspections settings page and apply changes. When you perform code analysis or execute a single inspection, you can specify which profile to use for each run.
Inspection profiles can be applicable on the IDE or on the project level:
- Project profiles are shared and accessible for the team members via VCS. They are stored in the project directory: <project>/.idea/inspectionProfiles.
- IDE profiles are intended for personal use only and are stored locally in XML files under the USER_HOME/.<PyCharm version>/config/inspection directory.
If necessary, you can change the applicability of the profile (current project of IDE) and, consequently, its location with the Share profile check box (selected means current project) in the Inspections settings page.
PyCharm comes with the following pre-defined inspection profiles:
- Default: This local (IDE level) profile is intended for personal use, applies to all projects, and is stored locally in the Default.xml file under the USER_HOME/.<PyCharm version>/config/inspection directory.
Project Default: when a new project is created, the
profile is copied from the
settings of a template project. This profile is shared and applies to the
After a project is created, any modifications to the project default profile will pass unnoticed to any other projects.
When the settings of the Project Default profile are modified in the Template Project settings, the changed profile will apply to all newly created projects, but the existing projects will not be affected as they already have a copy of this profile.
Project Default profile is stored in the Project_Default.xml file located in the <project>/.idea/inspectionProfiles directory.
One can have as many inspection profiles as required. There are two ways of creating new profiles: you can add a new profile as a copy of the Project Default profile or copy the currently selected profile. The newly created profiles are stored in XML files, located depending on the type of the base profile.
The <profile_name>.xml files representing inspection profiles appear whenever some changes to the profiles are done and applied. The files only store differences against the default profile.
Refer to the section Customizing Profiles for details.
Inspection severity indicates how seriously the code issues detected by the inspection impact the project and determines how the detected issues should be highlighted in the editor. By default, each inspection has one of the following severity levels:
- Server problem
- Weak Warning
You can increase or decrease the severity level of each inspection. That is, you can force PyCharm to display some warnings as errors or weak warnings. In a similar way, what is initially considered a weak warning can be displayed as a warning or error, or just as info.
You can also configure the color and font style used to highlight each severity level. Besides, you can create custom severity levels and set them for specific inspections.
If necessary, you can set different severity levels for the same inspection in different scopes.
For more information and procedural descriptions, see Configuring Inspection Severities.
By default, all enabled code inspections apply to all project files. If necessary, you can configure each code inspection (enable/disable, change its severity level and options) individually for different scopes. Such configurations, like any other inspection settings, are saved and applied as part of a specific profile.
There may be complicated cases when an inspection has different configurations associated with different scopes. When such inspection is executed in a file belonging to some or all of these scopes, the settings of the highest priority scope-specific configuration are applied. The priorities are defined by the relative position of the inspection's scope-specific configuration in inspection settings: the uppermost configuration has the highest priority. The Everywhere else configuration always has the lowest priority.
For more information and procedural descriptions, see Configuring Inspection for Different Scopes.
Examples of code inspections
In the Inspections page, all inspections are grouped into categories. The most common tasks covered by code analysis are:
- Finding probable bugs.
- Locating dead code.
- Detecting performance issues.
- Improving code structure and maintainability.
- Conforming to coding guidelines and standards.
- Conforming to specifications.
Find descriptions and examples of the various code inspections in the Inspections page of the Settings dialog. In this section, we'll consider several most prominent examples. In particular, PyCharm reports
1.2+Code incompatible with the current Python interpreter version:
Note that you can change the scope of versions in the inspection settings.
- Unresolved references:
- Duplicate keys in dictionaries:
- Dead code:
- Unused variables: