Add a batch of help examples (#1755)

crates/nu-cli/src/commands/alias.rs

@@ -1,4 +1,4 @@
-use crate::commands::{Example, WholeStreamCommand};
+use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;

crates/nu-cli/src/commands/append.rs

@@ -35,6 +35,13 @@ impl WholeStreamCommand for Append {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, append)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Add something to the end of a list or table",
+            example: "echo [1 2 3] | append 4",
+        }]
+    }
 }
 
 fn append(

crates/nu-cli/src/commands/autoview.rs

@@ -37,6 +37,19 @@ impl WholeStreamCommand for Autoview {
             name: args.call_info.name_tag,
         })
     }
+
+    fn examples(&self) -> &[Example] {
+        &[
+            Example {
+                description: "Automatically view the results",
+                example: "ls | autoview",
+            },
+            Example {
+                description: "Autoview is also implied. The above can be written as",
+                example: "ls",
+            },
+        ]
+    }
 }
 
 pub struct RunnableContextWithoutInput {

crates/nu-cli/src/commands/cal.rs

@@ -43,6 +43,19 @@ impl WholeStreamCommand for Cal {
     ) -> Result<OutputStream, ShellError> {
         cal(args, registry)
     }
+
+    fn examples(&self) -> &[Example] {
+        &[
+            Example {
+                description: "This month's calendar",
+                example: "cal",
+            },
+            Example {
+                description: "The calendar for all of 2012",
+                example: "cal --full-year 2012",
+            },
+        ]
+    }
 }
 
 pub fn cal(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {

crates/nu-cli/src/commands/calc.rs

@@ -24,6 +24,13 @@ impl WholeStreamCommand for Calc {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, calc)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Calculate math in the pipeline",
+            example: "echo '10 / 4' | calc",
+        }]
+    }
 }
 
 pub fn calc(

crates/nu-cli/src/commands/cd.rs

@@ -38,6 +38,27 @@ impl WholeStreamCommand for Cd {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, cd)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[
+            Example {
+                description: "Change to a new directory called 'dirname'",
+                example: "cd dirname",
+            },
+            Example {
+                description: "Change to your home directory",
+                example: "cd",
+            },
+            Example {
+                description: "Change to your home directory (alternate version)",
+                example: "cd ~",
+            },
+            Example {
+                description: "Change to the previous directory",
+                example: "cd -",
+            },
+        ]
+    }
 }
 
 fn cd(args: CdArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {

crates/nu-cli/src/commands/clear.rs

@@ -23,6 +23,12 @@ impl WholeStreamCommand for Clear {
     ) -> Result<OutputStream, ShellError> {
         clear(args, registry)
     }
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Clear the screen",
+            example: "clear",
+        }]
+    }
 }
 fn clear(_args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     if cfg!(windows) {

crates/nu-cli/src/commands/clip.rs

@@ -34,6 +34,13 @@ pub mod clipboard {
         ) -> Result<OutputStream, ShellError> {
             args.process(registry, clip)?.run()
         }
+
+        fn examples(&self) -> &[Example] {
+            &[Example {
+                description: "Save text to the clipboard",
+                example: "echo 'secret value' | clip",
+            }]
+        }
     }
 
     pub fn clip(

crates/nu-cli/src/commands/compact.rs

@@ -33,6 +33,13 @@ impl WholeStreamCommand for Compact {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, compact)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Remove all directory entries, except those with a 'target'",
+            example: "ls -af | compact target",
+        }]
+    }
 }
 
 pub fn compact(

crates/nu-cli/src/commands/count.rs

@@ -20,7 +20,7 @@ impl WholeStreamCommand for Count {
     }
 
     fn usage(&self) -> &str {
-        "Show the total number of rows."
+        "Show the total number of rows or items."
     }
 
     fn run(
@@ -30,6 +30,13 @@ impl WholeStreamCommand for Count {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, count)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Count the number of files/directories in the current directory",
+            example: "ls | count",
+        }]
+    }
 }
 
 pub fn count(

crates/nu-cli/src/commands/prepend.rs

@@ -35,6 +35,13 @@ impl WholeStreamCommand for Prepend {
     ) -> Result<OutputStream, ShellError> {
         args.process(registry, prepend)?.run()
     }
+
+    fn examples(&self) -> &[Example] {
+        &[Example {
+            description: "Add something to the end of a list or table",
+            example: "echo [2 3 4] | prepend 4",
+        }]
+    }
 }
 
 fn prepend(

crates/nu-cli/src/prelude.rs

@@ -72,6 +72,7 @@ pub(crate) use nu_protocol::{errln, out, outln};
 use nu_source::HasFallibleSpan;
 
 pub(crate) use crate::commands::command::{CommandArgs, RawCommandArgs, RunnableContext};
+pub(crate) use crate::commands::Example;
 pub(crate) use crate::context::CommandRegistry;
 pub(crate) use crate::context::Context;
 pub(crate) use crate::data::config;