Merge pull request #14 from mxcl/delete-noop

Delete noop

README.md

@@ -33,7 +33,7 @@ print(foo)         // => /bar/foo
 print(foo.isFile)  // => true
 
 // A practical example: installing a helper executable
-try Bundle.resources.join("helper").copy(into: Path.home.join(".local/bin").mkpath()).chmod(0o500)
+try Bundle.resources.join("helper").copy(into: Path.home.join(".local/bin").mkdir(.p)).chmod(0o500)
 ```
 
 We emphasize safety and correctness, just like Swift, and also (again like
@@ -184,6 +184,16 @@ Path("~/foo")!     // => /Users/mxcl/foo
 Path("~foo")       // => nil
 ```
 
+*Path.swift* has the general policty that if the desired end result preexists,
+then it’s a noop:
+
+* If you try to delete a file, but the file doesn't exist, we do nothing.
+* If you try to make a directory and it already exists, we do nothing.
+
+However notably if you try to copy or move a file with specifying `overwrite`
+and the file already exists at the destination and is identical, we don’t check
+for that as the check was deemed too expensive to be worthwhile.
+
 # Installation
 
 SwiftPM:

Sources/Path+Codable.swift

@@ -25,7 +25,7 @@ public extension CodingUserInfoKey {
 */
 extension Path: Codable {    
     /// - SeeAlso: `CodingUserInfoKey.relativePath`
-    // :nodoc:
+    /// :nodoc:
     public init(from decoder: Decoder) throws {
         let value = try decoder.singleValueContainer().decode(String.self)
         if value.hasPrefix("/") {
@@ -39,7 +39,7 @@ extension Path: Codable {
     }
 
     /// - SeeAlso: `CodingUserInfoKey.relativePath`
-    // :nodoc:
+    /// :nodoc:
     public func encode(to encoder: Encoder) throws {
         var container = encoder.singleValueContainer()
         if let root = encoder.userInfo[.relativePath] as? Path {

Sources/Path+FileManager.swift

@@ -5,10 +5,18 @@ public extension Path {
 
     /**
      Copies a file.
+
+         try Path.root.join("bar").copy(to: Path.home/"foo")
+         // => "/Users/mxcl/foo"
+
      - Note: `throws` if `to` is a directory.
      - Parameter to: Destination filename.
      - Parameter overwrite: If `true` and both `self` and `to` are files, overwrites `to`.
      - Note: If either `self` or `to are directories, `overwrite` is ignored.
+     - Note: Throws if `overwrite` is `false` yet `to` is *already* identical to
+      `self` because even though *Path.swift’s* policy is to noop if the desired
+       end result preexists, checking for this condition is too expensive a
+       trade-off.
      - Returns: `to` to allow chaining
      - SeeAlso: `copy(into:overwrite:)`
      */
@@ -24,15 +32,22 @@ public extension Path {
     /**
      Copies a file into a directory
 
+         try Path.root.join("bar").copy(into: .home)
+         // => "/Users/mxcl/bar"
+
+         // Create ~/.local/bin, copy `ls` there and make the new copy executable
+         try Path.root.join("bin/ls").copy(into: Path.home.join(".local/bin").mkdir(.p)).chmod(0o500)
+
      If the destination does not exist, this function creates the directory first.
-    
-        // Create ~/.local/bin, copy `ls` there and make the new copy executable
-        try Path.root.join("bin/ls").copy(into: Path.home.join(".local/bin").mkpath()).chmod(0o500)
 
-     - Note: `throws` if `into` is a file.
      - Parameter into: Destination directory
      - Parameter overwrite: If true overwrites any file that already exists at `into`.
      - Returns: The `Path` of the newly copied file.
+     - Note: `throws` if `into` is a file.
+     - Note: Throws if `overwrite` is `false` yet `to` is *already* identical to
+      `self` because even though *Path.swift’s* policy is to noop if the desired
+       end result preexists, checking for this condition is too expensive a
+       trade-off.
      - SeeAlso: `copy(into:overwrite:)`
      */
     @discardableResult
@@ -59,10 +74,18 @@ public extension Path {
 
     /**
      Moves a file.
-     - Note: `throws` if `to` is a directory.
+
+         try Path.root.join("bar").move(to: Path.home/"foo")
+         // => "/Users/mxcl/foo"
+
      - Parameter to: Destination filename.
      - Parameter overwrite: If true overwrites any file that already exists at `to`.
      - Returns: `to` to allow chaining
+     - Note: `throws` if `to` is a directory.
+     - Note: Throws if `overwrite` is `false` yet `to` is *already* identical to
+       `self` because even though *Path.swift’s* policy is to noop if the desired
+       end result preexists, checking for this condition is too expensive a
+       trade-off.
      - SeeAlso: move(into:overwrite:)
      */
     @discardableResult
@@ -77,18 +100,21 @@ public extension Path {
     /**
      Moves a file into a directory
 
+         try Path.root.join("bar").move(into: .home)
+         // => "/Users/mxcl/bar"
+
      If the destination does not exist, this function creates the directory first.
 
-     - Note: `throws` if `into` is a file.
      - Parameter into: Destination directory
-     - Parameter overwrite: If true overwrites any file that already exists at `into`.
+     - Parameter overwrite: If true *overwrites* any file that already exists at `into`.
+     - Note: `throws` if `into` is a file.
      - Returns: The `Path` of destination filename.
      - SeeAlso: move(into:overwrite:)
      */
     @discardableResult
     func move(into: Path) throws -> Path {
         if !into.exists {
-            try into.mkpath()
+            try into.mkdir(.p)
         } else if !into.isDirectory {
             throw CocoaError.error(.fileWriteFileExists)
         }
@@ -97,10 +123,16 @@ public extension Path {
         return rv
     }
 
-    /// Deletes the path, recursively if a directory.
+    /**
+     Deletes the path, recursively if a directory.
+     - Note: noop: if the path doesn’t exist
+     ∵ *Path.swift* doesn’t error if desired end result preexists.
+    */
     @inlinable
     func delete() throws {
-        try FileManager.default.removeItem(at: url)
+        if exists {
+            try FileManager.default.removeItem(at: url)
+        }
     }
 
     /**
@@ -113,49 +145,37 @@ public extension Path {
         return try "".write(to: self)
     }
 
-    /// Helper due to Linux Swift being incomplete.
-    private func _foo(go: () throws -> Void) throws {
-    #if !os(Linux)
+    /**
+     Creates the directory at this path.
+     - Note: Does not create any intermediary directories.
+     - Parameter options: Specify `mkdir(.p)` to create intermediary directories.
+     - Note: We do not error if the directory already exists (even without `.p`)
+       because *Path.swift* noops if the desired end result preexists.
+     - Returns: `self` to allow chaining.
+     */
+    @discardableResult
+    func mkdir(_ options: MakeDirectoryOptions? = nil) throws -> Path {
         do {
-            try go()
+            let wid = options == .p
+            try FileManager.default.createDirectory(at: self.url, withIntermediateDirectories: wid, attributes: nil)
         } catch CocoaError.Code.fileWriteFileExists {
-            // noop
-        }
-    #else
-        do {
-            try go()
+            //noop (fails to trigger on Linux)
         } catch {
+        #if os(Linux)
             let error = error as NSError
             guard error.domain == NSCocoaErrorDomain, error.code == CocoaError.Code.fileWriteFileExists.rawValue else {
                 throw error
             }
-        }
-    #endif
-    }
-
-    /**
-     Creates the directory at this path.
-     - Note: Does not create any intermediary directories.
-     - Returns: `self` to allow chaining.
-     */
-    @discardableResult
-    func mkdir() throws -> Path {
-        try _foo {
-            try FileManager.default.createDirectory(at: self.url, withIntermediateDirectories: false, attributes: nil)
+        #else
+            throw error
+        #endif
         }
         return self
     }
+}
 
-    /**
-     Creates the directory at this path.
-     - Note: Creates any intermediary directories, if required.
-     - Returns: `self` to allow chaining.
-     */
-    @discardableResult
-    func mkpath() throws -> Path {
-        try _foo {
-            try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true, attributes: nil)
-        }
-        return self
-    }
+/// Options for `Path.mkdir`
+public enum MakeDirectoryOptions {
+    /// Creates intermediary directories. Works the same as mkdir -p.
+    case p
 }

Tests/PathTests/PathTests.swift

@@ -83,7 +83,7 @@ class PathTests: XCTestCase {
         try Path.mktemp {
             for _ in 0...1 {
                 try $0.join("a").mkdir()
-                try $0.join("b/c").mkpath()
+                try $0.join("b/c").mkdir(.p)
             }
         }
     }