Add Support for Example Code

src/nimble.nim

@@ -157,14 +157,23 @@ proc buildFromDir(pkgInfo: PackageInfo, paths: HashSet[string],
   ## Builds a package as specified by ``pkgInfo``.
   # Handle pre-`build` hook.
   let
-    realDir = pkgInfo.getRealDir()
     pkgDir = pkgInfo.myPath.parentDir()
+    realDir =
+      if options.example:
+        pkgInfo.getRealExamplesDir()
+      else:
+        pkgInfo.getRealDir()
+    bin =
+      if options.example:
+        pkgInfo.getExampleBin()
+      else:
+        pkgInfo.bin
 
   cd pkgDir: # Make sure `execHook` executes the correct .nimble file.
     if not execHook(options, actionBuild, true):
       raise nimbleError("Pre-hook prevented further execution.")
 
-  if pkgInfo.bin.len == 0:
+  if bin.len == 0:
     raise nimbleError(
         "Nothing to build. Did you specify a module to build using the" &
         " `bin` key in your .nimble file?")
@@ -181,6 +190,8 @@ proc buildFromDir(pkgInfo: PackageInfo, paths: HashSet[string],
   if options.verbosity == SilentPriority:
     # Hide Nim warnings
     args.add("--warnings:off")
+  if options.example:
+    args.add("--path:" & pkgInfo.srcDir.quoteShell)
 
   let binToBuild =
     # Only build binaries specified by user if any, but only if top-level package,
@@ -189,13 +200,13 @@ proc buildFromDir(pkgInfo: PackageInfo, paths: HashSet[string],
       options.getCompilationBinary(pkgInfo).get("")
     else: ""
 
-  for bin, src in pkgInfo.bin:
+  for bin, src in bin:
     # Check if this is the only binary that we want to build.
     if binToBuild.len != 0 and binToBuild != bin:
       if bin.extractFilename().changeFileExt("") != binToBuild:
         continue
 
-    let outputDir = pkgInfo.getOutputDir("")
+    let outputDir = pkgInfo.getOutputDir("", options.example)
     if dirExists(outputDir):
       if fileExists(outputDir / bin):
         if not pkgInfo.needsRebuild(outputDir / bin, realDir, options):
@@ -206,7 +217,7 @@ proc buildFromDir(pkgInfo: PackageInfo, paths: HashSet[string],
     else:
       createDir(outputDir)
 
-    let outputOpt = "-o:" & pkgInfo.getOutputDir(bin).quoteShell
+    let outputOpt = "-o:" & pkgInfo.getOutputDir(bin, options.example).quoteShell
     display("Building", "$1/$2 using $3 backend" %
             [pkginfo.basicInfo.name, bin, pkgInfo.backend], priority = HighPriority)
 
@@ -724,7 +735,11 @@ proc clean(options: Options) =
 
 proc execBackend(pkgInfo: PackageInfo, options: Options) =
   let
-    bin = options.getCompilationBinary(pkgInfo).get("")
+    bin =
+      if options.example:
+        pkgInfo.getRealExamplesDir() / options.getCompilationBinary(pkgInfo).get("")
+      else:
+        options.getCompilationBinary(pkgInfo).get("")
     binDotNim = bin.addFileExt("nim")
 
   if bin == "":
@@ -750,6 +765,8 @@ proc execBackend(pkgInfo: PackageInfo, options: Options) =
   if options.verbosity == SilentPriority:
     # Hide Nim warnings
     args.add("--warnings:off")
+  if options.example:
+    args.add("--path:" & pkgInfo.srcDir.quoteShell)
 
   for option in options.getCompilationFlags():
     args.add(option.quoteShell)
@@ -1918,7 +1935,7 @@ proc run(options: Options) =
   if binary.len == 0:
     raise nimbleError("Please specify a binary to run")
 
-  if binary notin pkgInfo.bin:
+  if not options.example and binary notin pkgInfo.bin:
     raise nimbleError(binaryNotDefinedInPkgMsg(binary, pkgInfo.basicInfo.name))
 
   if pkgInfo.isLink:
@@ -1927,7 +1944,7 @@ proc run(options: Options) =
   elif options.getCompilationFlags.len > 0:
     displayWarning(ignoringCompilationFlagsMsg)
 
-  let binaryPath = pkgInfo.getOutputDir(binary)
+  let binaryPath = pkgInfo.getOutputDir(binary, options.example)
   let cmd = quoteShellCommand(binaryPath & options.action.runFlags)
   displayDebug("Executing", cmd)
 

src/nimblepkg/init.nim

@@ -1,4 +1,4 @@
-import os, strutils
+import os, strutils, std/options
 
 import ./cli, ./tools
 
@@ -20,6 +20,36 @@ proc writeExampleIfNonExistent(file: string, content: string) =
     display("Info:", "File " & file & " already exists, did not write " &
             "example code", priority = HighPriority)
 
+proc exampleCode(info: PkgInitInfo): Option[string] =
+  case info.pkgType
+  of "library":
+    result = some("""
+# You may create as many example files as you want. Example file names should
+# be valid Nim module names.
+#
+# To run this example, simply execute `nimble run --example example1`.
+
+import $1
+
+echo "One plus one equals ", $$add(1, 1)
+
+""" % info.pkgName)
+
+  of "hybrid":
+    result = some("""
+# You may create as many example files as you want. Example file names should
+# be valid Nim module names.
+#
+# To run this example, simply execute `nimble run --example example1`.
+
+import $1pkg/submodule
+
+echo getWelcomeMessage()
+
+""" % info.pkgName)
+  else:
+    discard
+
 proc createPkgStructure*(info: PkgInitInfo, pkgRoot: string) =
   # Create source directory
   createDirD(pkgRoot / info.pkgSrcDir)
@@ -154,6 +184,17 @@ test "correct welcome":
   else:
     assert false, "Invalid package type specified."
 
+  # Create examples directory and dummy example
+  let pkgExamplesDir = "examples"
+  let pkgExampleCode = exampleCode(info)
+  if pkgExampleCode.isSome():
+    let pkgExampleCode = pkgExampleCode.get("")
+    let pkgExamplesPath = pkgRoot / pkgExamplesDir
+
+    createDirD(pkgExamplesPath)
+    nimbleFileOptions.add("# examplesDir   = $1    # Uncomment to change the name of the examples directory\n" % pkgExamplesDir.escape())
+    writeExampleIfNonExistent(pkgExamplesPath / "example1".addFileExt(".nim"), pkgExampleCode)
+
   # Write the nimble file
   let nimbleFile = pkgRoot / info.pkgName.changeFileExt("nimble")
   writeFile(nimbleFile, """# Package

src/nimblepkg/nimscriptapi.nim

@@ -24,6 +24,7 @@ var
   srcDir*: string      ## The package's source directory.
   binDir*: string      ## The package's binary directory.
   backend*: string     ## The package's backend.
+  examplesDir*: string ## The package's examples directory.
 
   skipDirs*, skipFiles*, skipExt*, installDirs*, installFiles*,
     installExt*, bin*: seq[string] = @[] ## Nimble metadata.
@@ -126,6 +127,7 @@ proc printPkgInfo(): string =
   printIfLen srcDir
   printIfLen binDir
   printIfLen backend
+  printIfLen examplesDir
 
   printSeqIfLen skipDirs
   printSeqIfLen skipFiles

src/nimblepkg/options.nim

@@ -31,6 +31,7 @@ type
     showVersion*: bool
     offline*: bool
     noColor*: bool
+    example*: bool
     disableValidation*: bool
     continueTestsOnFailure*: bool
     ## Whether packages' repos should always be downloaded with their history.
@@ -56,6 +57,7 @@ type
     actionUninstall, actionCompile, actionDoc, actionCustom, actionTasks,
     actionDevelop, actionCheck, actionLock, actionRun, actionSync, actionSetup,
     actionClean, actionDeps
+
 
   DevelopActionType* = enum
     datAdd, datRemoveByPath, datRemoveByName, datInclude, datExclude
@@ -223,6 +225,7 @@ Nimble Options:
       --silent                    Hide all Nimble and Nim output
       --verbose                   Show all non-debug output.
       --debug                     Show all output including debug messages.
+      --example                   Build/run an example instead of a package.
       --offline                   Don't use network.
       --noColor                   Don't colorise output.
       --noSSLCheck                Don't check SSL certificates.
@@ -517,6 +520,7 @@ proc parseFlag*(flag, val: string, result: var Options, kind = cmdLongOption) =
   of "tarballs", "t": result.enableTarballs = true
   of "package", "p": result.package = val
   of "lock-file": result.lockFileName = val
+  of "example": result.example = true
   else: isGlobalFlag = false
 
   var wasFlagHandled = true

src/nimblepkg/packageinfo.nim

@@ -367,15 +367,30 @@ proc getRealDir*(pkgInfo: PackageInfo): string =
   else:
     result = pkgInfo.getNimbleFileDir()
 
-proc getOutputDir*(pkgInfo: PackageInfo, bin: string): string =
+proc getOutputDir*(pkgInfo: PackageInfo, bin: string, example = false): string =
   ## Returns a binary output dir for the package.
-  if pkgInfo.binDir != "":
-    result = pkgInfo.getNimbleFileDir() / pkgInfo.binDir / bin
+  if example and pkgInfo.examplesDir != "":
+    if pkgInfo.binDir != "":
+      result = pkgInfo.getNimbleFileDir() / pkgInfo.binDir / pkgInfo.examplesDir / bin
+    else:
+      result = pkgInfo.mypath.splitFile.dir / pkgInfo.examplesDir / bin
   else:
-    result = pkgInfo.mypath.splitFile.dir / bin
+    if pkgInfo.binDir != "":
+      result = pkgInfo.getNimbleFileDir() / pkgInfo.binDir / bin
+    else:
+      result = pkgInfo.mypath.splitFile.dir / bin
   if bin.len != 0 and dirExists(result):
     result &= ".out"
 
+proc getRealExamplesDir*(pkgInfo: PackageInfo): string =
+  ## Returns the directory containing the example source files.
+  ## If no example directory was specified in the package info, "examples"
+  ## is returned.
+  if pkgInfo.examplesDir != "" and (not pkgInfo.isInstalled or pkgInfo.isLink):
+    result = pkgInfo.getNimbleFileDir() / pkgInfo.examplesDir
+  elif not pkgInfo.isInstalled or pkgInfo.isLink:
+    result = "examples"
+
 proc echoPackage*(pkg: Package) =
   echo(pkg.name & ":")
   if pkg.alias.len > 0:
@@ -530,6 +545,20 @@ proc hash*(x: PackageInfo): Hash =
 proc getNameAndVersion*(pkgInfo: PackageInfo): string =
   &"{pkgInfo.basicInfo.name}@{pkgInfo.basicInfo.version}"
 
+proc getExampleBin*(pkgInfo: PackageInfo): Table[string,string] =
+  let examplesDir = pkgInfo.getRealExamplesDir()
+  if examplesDir == "":
+    raise nimbleError("Cannot find example files", hint="Was 'examplesDir' defined in '$1' ?" % pkgInfo.myPath)
+
+  if not examplesDir.dirExists():
+    raise nimbleError("Examples directory not found: $1" % examplesDir)
+
+  for kind, path in walkDir(examplesDir):
+    if kind in {pcFile, pcLinkToFile}:
+      let (_, name, ext) = path.splitFile()
+      if ext == ".nim":
+        result[name] = name
+
 when isMainModule:
   import unittest
 

src/nimblepkg/packageinfotypes.nim

@@ -58,6 +58,7 @@ type
     bin*: Table[string, string]
     binDir*: string
     srcDir*: string
+    examplesDir*: string
     backend*: string
     foreignDeps*: seq[string]
     basicInfo*: PackageBasicInfo

src/nimblepkg/packageparser.nim

@@ -238,6 +238,7 @@ proc readPackageInfoFromNimble(path: string; result: var PackageInfo) =
           of "license": result.license = ev.value
           of "srcdir": result.srcDir = ev.value
           of "bindir": result.binDir = ev.value
+          of "examplesdir": result.examplesDir = ev.value
           of "skipdirs":
             result.skipDirs.add(ev.value.multiSplit)
           of "skipfiles":