Fmbm.DirPaths 1.0.1

DirPaths

A tiny tool for locating local application directories. E.g.:

  │
  ├── LoremIpsum
  │
  └── <AppRoot>
          │
          ├── bin
          │
          ├── etc
          │
          ├── data
          │
          └── log

Features:

• Default rules for determining the AppRoot without configuration.
• Custom rules for determining the AppRoot.
• Configure alternate paths for top level subdirectories.
• Thread Safe.

For Me, By Me (FMBM)

This package is primarily intended for use by the author. It has only been tested with Console applications on Windows and MacOS. It intended for getting ad-hoc applications up and running quickly. It probably is not suitable for complex, production, nor evolving projects. (The name is inspired by the Fubu, For Us, By Us, project, but there is no other connection.)

Contents

• Usage
• Set Before Get
• Default AppRoot
• Changing The AppRoot
• AppRoot Presets
• Path Tools
• Extensibility
• Examples

Usage

archive, data, download, etc, log, temp and upload are predefined. Other top level directories can be accessed using GetDir(name).

The Path property returns the path for the directory. CheckedPath first checks if the directory exists and creates it if doesn't exist.

    using Fmbm.IO;

    // Get path for <AppRoot>/etc but do not create it if it does not exist
    string etcDir = DirPaths.EtcDir.Path;

    // Get path for <AppRoot>/temp and create it if needed
    string tempDir = DirPaths.TempDir.CheckedPath;

    // Get path for <AppRoot>/cats (and create it if needed)
    string catDir = DirPaths.GetDir("cats").CheckedPath;

    // Specify custom path for 'data' and 'dog'.
    DirPaths.DataDir.Path = "FMBM_Sample/Data";
    DirPaths.GetDir("dog").Path = "FMBM_Sample\Canine";

Set Before Get

No Path property can be set after it has been got. So all gets of a given Path property will always return the same value (or all will throw the same exception).

Path can be set any number of times before it it is got.

By default AppRoot and subdirectories will have non-null values.

The AppRoot Path can be cleared. An InvalidOperationException will be thrown if Path's value is got while it is clear. (I.e. before a new value has been set.)

Default AppRoot

The default DirPaths.AppRoot.Path will be set by the first successful rule:

1. Use the value stored in the FMBM_APPROOT environment variable.

2. If the name of the Base directory (see 4. below) is bin then use the parent of that directory as the AppRoot. E.g., if the Base directory is ...\apps\myapp\bin then ...\apps\myapp\ will be the AppRoot. This is useful for deploying applications using a tree structure similar to that at the top of this page and the executable is in the bin directory.

3. If one of the parent directories of the Base directory is named bin then use a sibling of that bin directory named AppRoot. This is useful for running the application under Visual Studio. E.g., If the Base directory is ...\Project\bin\Debug\net9.0 then the AppRoot will be: ...\Project\AppRoot\.
   
   However, if the application is a Debug build and the directory AppRoot-Debug already exists, then that will be used instead. It will not be used automatically, only if the directory has already been manually created beforehand. (This would allow Release and Debug builds to run with different environments.)

4. If none of the above rules match, then use the Base directory. This is usually the directory containing the application's executable.

Changing The AppRoot

The AppRoot.Path can only be set before its value has been read.

Runtime

The AppRoot can be changed at runtime by setting the FMBM_APPROOT environment variable.

SetAppRoot

DirPaths.SetAppRoot(path1, path2, ...) is a helper function that takes an arbitrary number of strings, if any are non-null it sets the AppRoot to the first non-null value and returns true. If all the values are null then the AppRoot path is unchanged and it returns false.

ClearAppRoot

DirPaths.ClearAppRoot() clears any AppRoot path. This is useful if you do not want to use the default path and to make sure only an explicitly set path is used.

AppRoot.Path

DirPaths.AppRoot.Path can be set directly, like subdirectories can, it will not accept a null value.

AppRoot Presets

The RootPresets class contains properties and methods for some predefined rules for choosing the AppRoot directory.

• RootPresets.Base The applications Base directory. (Used by the fourth rule for finding the Default AppRoot.)

• RootPresets.Current The process's current working directory.

• RootPresets.Environment() The value stored in the FMBM_APPROOT environment variable. (Used by the first rule to find the Default AppRoot.) - can be null.

• RootPresets.Environment(NAME) The value stored in the <NAME> environment variable - can be null.

• RootPresets.BinParent() The value described in the second rule to find the Default AppRoot - can be null.

• RootPresets.AnyBinAppRootSibling() The value described in the third rule to find the Default AppRoot - can be null.

• RootPresets.Fmbm() The function that combines all four rules to find the Default AppRoot.

• RootPresets.Fmbm(NAME) The same as FMBM() except it checks the <NAME> environment variable instead of the FMBM_APPROOT environment variable.

PathTools

Namespace: Fmbm.IO.StringExtensions

The PathTools class contains helper methods used by RootPesets. These are extension methods of string. They use null to indicate failure so all the methods can accept null as input, which would then be the return value. Name comparison is case insensitive.

• path.NameIs(name) returns path if the directory's name matches name otherwise null.

• path.Parent() return path's parent path or null if path is the root directory or path is null.

• path.SearchUp(name) if path or any of its parent directories match the name name then that directory's path is returned, otherwise null.

• path.SubDir(name) the subdirectory of path with name name, or null if path is null.

• path.Sibling(name) is equivalent to path.Parent().SubDir(name)

• path.ExistingDebug() if the application is a Debug build and a sibling to path already exists that has the name <name>-Debug then the path to <name>-Debug is returned, otherwise path is returned.

Extensibility

None.

Examples

These are examples of how to set the AppRoot. See usage above for examples of how to get and set the path of its sub directories.

Set a hard coded path

DirPaths.SetAppRoot(@"C:\Apple\Banana\Cherry");

// EtcDir.Path is C:\Apple\Banana\Cherry\etc

Use the value of a the FRUIT_APPROOT environment variable but fallback to default AppRoot if the environment variable is not set:

Environment.SetEnvironmentVariable("FRUIT_APPROOT", @"D:\Fruity");
DirPaths.SetAppRoot(RootPresets.Environment("FRUIT_APPROOT"));

// EtcDir.Path is D:\Fruity\etc or the default <AppRoot>\etc if the
// environment variable is not set.

Use the value of a the FRUIT_APPROOT environment variable but throw an exception if the environment variable is not set:

// If the environment variable is set:
DirPaths.ClearAppRoot();
Environment.SetEnvironmentVariable("FRUIT_APPROOT", @"D:\Fruity");
DirPaths.SetAppRoot(RootPresets.Environment("FRUIT_APPROOT"));

// EtcDir.Path is D:\Fruity\etc

// Or if the environment variable is not set:
DirPaths.ClearAppRoot();
DirPaths.SetAppRoot(RootPresets.EnvironmentVariable("FRUIT_APPROOT"));

// InvalidOperationException is thrown when EtcDir.Path is got.

If the Base directory is named Cherry then use its parent as the AppRoot (otherwise fallback to the default):

DirPaths.SetAppRoot(RootPresets.Base.NameIs("Cherry").Parent());

// If the Base directory is C:\Apple\Banana\Cherry then EtcDir.Path is 
// C:\Apple\Banana\etc

If any parent of the Base directory is called Apple then use a sibling of that directory named Basket, otherwise fail:

DirPaths.ClearAppRoot();
DirPaths.SetAppRoot(RootPresets.Base.SearchUp("Apple").Sibling("Basket"));

// If the Base directory is C:\Apple\Banana\Cherry then EtcDir.Path is 
// C:\Basket\etc. If 'Apple' is not found then an InvalidOperationException
// is thrown.
 

Use the process's Current working directory:

DirPaths.SetAppRoot(RootPresets.Current);

Try four of the above rules and use the first that works:

DirPaths.ClearAppRoot();
DirPaths.SetAppRoot(
    RootPresets.Environment("FRUIT_APPROOT"),
    RootPresets.Base.NameIs("Cherry").Parent(),
    RootPresets.Base.SearchUp("Apple").Sibling("Basket"),
    RootPresets.Current
);

The ClearAppRoot() in the above shouldn't have any effect in this case because RootPresets.Current should always have a non-null value so it should never fallback to the default path.