auto merge of #12401 : alexcrichton/rust/if-ok-2-try, r=brson

This "bubble up an error" macro was originally named if_ok! in order to get it
landed, but after the fact it was discovered that this name is not exactly
desirable.

The name `if_ok!` isn't immediately clear that is has much to do with error
handling, and it doesn't look fantastic in all contexts (if if_ok!(...) {}). In
general, the agreed opinion about `if_ok!` is that is came in as subpar.

The name `try!` is more invocative of error handling, it's shorter by 2 letters,
and it looks fitting in almost all circumstances. One concern about the word
`try!` is that it's too invocative of exceptions, but the belief is that this
will be overcome with documentation and examples.

Close #12037

Author: bors

src/libextra/json.rs

@@ -246,7 +246,7 @@ use serialize::Encodable;
 use serialize;
 use collections::TreeMap;
 
-macro_rules! if_ok( ($e:expr) => (
+macro_rules! try( ($e:expr) => (
     match $e { Ok(e) => e, Err(e) => { self.error = Err(e); return } }
 ) )
 
@@ -342,7 +342,7 @@ impl<'a> Encoder<'a> {
 }
 
 impl<'a> serialize::Encoder for Encoder<'a> {
-    fn emit_nil(&mut self) { if_ok!(write!(self.wr, "null")) }
+    fn emit_nil(&mut self) { try!(write!(self.wr, "null")) }
 
     fn emit_uint(&mut self, v: uint) { self.emit_f64(v as f64); }
     fn emit_u64(&mut self, v: u64) { self.emit_f64(v as f64); }
@@ -358,20 +358,20 @@ impl<'a> serialize::Encoder for Encoder<'a> {
 
     fn emit_bool(&mut self, v: bool) {
         if v {
-            if_ok!(write!(self.wr, "true"));
+            try!(write!(self.wr, "true"));
         } else {
-            if_ok!(write!(self.wr, "false"));
+            try!(write!(self.wr, "false"));
         }
     }
 
     fn emit_f64(&mut self, v: f64) {
-        if_ok!(write!(self.wr, "{}", f64::to_str_digits(v, 6u)))
+        try!(write!(self.wr, "{}", f64::to_str_digits(v, 6u)))
     }
     fn emit_f32(&mut self, v: f32) { self.emit_f64(v as f64); }
 
     fn emit_char(&mut self, v: char) { self.emit_str(str::from_char(v)) }
     fn emit_str(&mut self, v: &str) {
-        if_ok!(write!(self.wr, "{}", escape_str(v)))
+        try!(write!(self.wr, "{}", escape_str(v)))
     }
 
     fn emit_enum(&mut self, _name: &str, f: |&mut Encoder<'a>|) { f(self) }
@@ -385,19 +385,19 @@ impl<'a> serialize::Encoder for Encoder<'a> {
         // Bunny => "Bunny"
         // Kangaroo(34,"William") => {"variant": "Kangaroo", "fields": [34,"William"]}
         if cnt == 0 {
-            if_ok!(write!(self.wr, "{}", escape_str(name)));
+            try!(write!(self.wr, "{}", escape_str(name)));
         } else {
-            if_ok!(write!(self.wr, "\\{\"variant\":"));
-            if_ok!(write!(self.wr, "{}", escape_str(name)));
-            if_ok!(write!(self.wr, ",\"fields\":["));
+            try!(write!(self.wr, "\\{\"variant\":"));
+            try!(write!(self.wr, "{}", escape_str(name)));
+            try!(write!(self.wr, ",\"fields\":["));
             f(self);
-            if_ok!(write!(self.wr, "]\\}"));
+            try!(write!(self.wr, "]\\}"));
         }
     }
 
     fn emit_enum_variant_arg(&mut self, idx: uint, f: |&mut Encoder<'a>|) {
         if idx != 0 {
-            if_ok!(write!(self.wr, ","));
+            try!(write!(self.wr, ","));
         }
         f(self);
     }
@@ -418,17 +418,17 @@ impl<'a> serialize::Encoder for Encoder<'a> {
     }
 
     fn emit_struct(&mut self, _: &str, _: uint, f: |&mut Encoder<'a>|) {
-        if_ok!(write!(self.wr, r"\{"));
+        try!(write!(self.wr, r"\{"));
         f(self);
-        if_ok!(write!(self.wr, r"\}"));
+        try!(write!(self.wr, r"\}"));
     }
 
     fn emit_struct_field(&mut self,
                          name: &str,
                          idx: uint,
                          f: |&mut Encoder<'a>|) {
-        if idx != 0 { if_ok!(write!(self.wr, ",")) }
-        if_ok!(write!(self.wr, "{}:", escape_str(name)));
+        if idx != 0 { try!(write!(self.wr, ",")) }
+        try!(write!(self.wr, "{}:", escape_str(name)));
         f(self);
     }
 
@@ -454,31 +454,31 @@ impl<'a> serialize::Encoder for Encoder<'a> {
     fn emit_option_some(&mut self, f: |&mut Encoder<'a>|) { f(self); }
 
     fn emit_seq(&mut self, _len: uint, f: |&mut Encoder<'a>|) {
-        if_ok!(write!(self.wr, "["));
+        try!(write!(self.wr, "["));
         f(self);
-        if_ok!(write!(self.wr, "]"));
+        try!(write!(self.wr, "]"));
     }
 
     fn emit_seq_elt(&mut self, idx: uint, f: |&mut Encoder<'a>|) {
         if idx != 0 {
-            if_ok!(write!(self.wr, ","));
+            try!(write!(self.wr, ","));
         }
         f(self)
     }
 
     fn emit_map(&mut self, _len: uint, f: |&mut Encoder<'a>|) {
-        if_ok!(write!(self.wr, r"\{"));
+        try!(write!(self.wr, r"\{"));
         f(self);
-        if_ok!(write!(self.wr, r"\}"));
+        try!(write!(self.wr, r"\}"));
     }
 
     fn emit_map_elt_key(&mut self, idx: uint, f: |&mut Encoder<'a>|) {
-        if idx != 0 { if_ok!(write!(self.wr, ",")) }
+        if idx != 0 { try!(write!(self.wr, ",")) }
         f(self)
     }
 
     fn emit_map_elt_val(&mut self, _idx: uint, f: |&mut Encoder<'a>|) {
-        if_ok!(write!(self.wr, ":"));
+        try!(write!(self.wr, ":"));
         f(self)
     }
 }
@@ -503,7 +503,7 @@ impl<'a> PrettyEncoder<'a> {
 }
 
 impl<'a> serialize::Encoder for PrettyEncoder<'a> {
-    fn emit_nil(&mut self) { if_ok!(write!(self.wr, "null")); }
+    fn emit_nil(&mut self) { try!(write!(self.wr, "null")); }
 
     fn emit_uint(&mut self, v: uint) { self.emit_f64(v as f64); }
     fn emit_u64(&mut self, v: u64) { self.emit_f64(v as f64); }
@@ -519,20 +519,20 @@ impl<'a> serialize::Encoder for PrettyEncoder<'a> {
 
     fn emit_bool(&mut self, v: bool) {
         if v {
-            if_ok!(write!(self.wr, "true"));
+            try!(write!(self.wr, "true"));
         } else {
-            if_ok!(write!(self.wr, "false"));
+            try!(write!(self.wr, "false"));
         }
     }
 
     fn emit_f64(&mut self, v: f64) {
-        if_ok!(write!(self.wr, "{}", f64::to_str_digits(v, 6u)));
+        try!(write!(self.wr, "{}", f64::to_str_digits(v, 6u)));
     }
     fn emit_f32(&mut self, v: f32) { self.emit_f64(v as f64); }
 
     fn emit_char(&mut self, v: char) { self.emit_str(str::from_char(v)) }
     fn emit_str(&mut self, v: &str) {
-        if_ok!(write!(self.wr, "{}", escape_str(v)));
+        try!(write!(self.wr, "{}", escape_str(v)));
     }
 
     fn emit_enum(&mut self, _name: &str, f: |&mut PrettyEncoder<'a>|) {
@@ -545,24 +545,24 @@ impl<'a> serialize::Encoder for PrettyEncoder<'a> {
                          cnt: uint,
                          f: |&mut PrettyEncoder<'a>|) {
         if cnt == 0 {
-            if_ok!(write!(self.wr, "{}", escape_str(name)));
+            try!(write!(self.wr, "{}", escape_str(name)));
         } else {
             self.indent += 2;
-            if_ok!(write!(self.wr, "[\n{}{},\n", spaces(self.indent),
+            try!(write!(self.wr, "[\n{}{},\n", spaces(self.indent),
                           escape_str(name)));
             f(self);
             self.indent -= 2;
-            if_ok!(write!(self.wr, "\n{}]", spaces(self.indent)));
+            try!(write!(self.wr, "\n{}]", spaces(self.indent)));
         }
     }
 
     fn emit_enum_variant_arg(&mut self,
                              idx: uint,
                              f: |&mut PrettyEncoder<'a>|) {
         if idx != 0 {
-            if_ok!(write!(self.wr, ",\n"));
+            try!(write!(self.wr, ",\n"));
         }
-        if_ok!(write!(self.wr, "{}", spaces(self.indent)));
+        try!(write!(self.wr, "{}", spaces(self.indent)));
         f(self)
     }
 
@@ -587,13 +587,13 @@ impl<'a> serialize::Encoder for PrettyEncoder<'a> {
                    len: uint,
                    f: |&mut PrettyEncoder<'a>|) {
         if len == 0 {
-            if_ok!(write!(self.wr, "\\{\\}"));
+            try!(write!(self.wr, "\\{\\}"));
         } else {
-            if_ok!(write!(self.wr, "\\{"));
+            try!(write!(self.wr, "\\{"));
             self.indent += 2;
             f(self);
             self.indent -= 2;
-            if_ok!(write!(self.wr, "\n{}\\}", spaces(self.indent)));
+            try!(write!(self.wr, "\n{}\\}", spaces(self.indent)));
         }
     }
 
@@ -602,11 +602,11 @@ impl<'a> serialize::Encoder for PrettyEncoder<'a> {
                          idx: uint,
                          f: |&mut PrettyEncoder<'a>|) {
         if idx == 0 {
-            if_ok!(write!(self.wr, "\n"));
+            try!(write!(self.wr, "\n"));
         } else {
-            if_ok!(write!(self.wr, ",\n"));
+            try!(write!(self.wr, ",\n"));
         }
-        if_ok!(write!(self.wr, "{}{}: ", spaces(self.indent), escape_str(name)));
+        try!(write!(self.wr, "{}{}: ", spaces(self.indent), escape_str(name)));
         f(self);
     }
 
@@ -635,50 +635,50 @@ impl<'a> serialize::Encoder for PrettyEncoder<'a> {
 
     fn emit_seq(&mut self, len: uint, f: |&mut PrettyEncoder<'a>|) {
         if len == 0 {
-            if_ok!(write!(self.wr, "[]"));
+            try!(write!(self.wr, "[]"));
         } else {
-            if_ok!(write!(self.wr, "["));
+            try!(write!(self.wr, "["));
             self.indent += 2;
             f(self);
             self.indent -= 2;
-            if_ok!(write!(self.wr, "\n{}]", spaces(self.indent)));
+            try!(write!(self.wr, "\n{}]", spaces(self.indent)));
         }
     }
 
     fn emit_seq_elt(&mut self, idx: uint, f: |&mut PrettyEncoder<'a>|) {
         if idx == 0 {
-            if_ok!(write!(self.wr, "\n"));
+            try!(write!(self.wr, "\n"));
         } else {
-            if_ok!(write!(self.wr, ",\n"));
+            try!(write!(self.wr, ",\n"));
         }
-        if_ok!(write!(self.wr, "{}", spaces(self.indent)));
+        try!(write!(self.wr, "{}", spaces(self.indent)));
         f(self)
     }
 
     fn emit_map(&mut self, len: uint, f: |&mut PrettyEncoder<'a>|) {
         if len == 0 {
-            if_ok!(write!(self.wr, "\\{\\}"));
+            try!(write!(self.wr, "\\{\\}"));
         } else {
-            if_ok!(write!(self.wr, "\\{"));
+            try!(write!(self.wr, "\\{"));
             self.indent += 2;
             f(self);
             self.indent -= 2;
-            if_ok!(write!(self.wr, "\n{}\\}", spaces(self.indent)));
+            try!(write!(self.wr, "\n{}\\}", spaces(self.indent)));
         }
     }
 
     fn emit_map_elt_key(&mut self, idx: uint, f: |&mut PrettyEncoder<'a>|) {
         if idx == 0 {
-            if_ok!(write!(self.wr, "\n"));
+            try!(write!(self.wr, "\n"));
         } else {
-            if_ok!(write!(self.wr, ",\n"));
+            try!(write!(self.wr, ",\n"));
         }
-        if_ok!(write!(self.wr, "{}", spaces(self.indent)));
+        try!(write!(self.wr, "{}", spaces(self.indent)));
         f(self);
     }
 
     fn emit_map_elt_val(&mut self, _idx: uint, f: |&mut PrettyEncoder<'a>|) {
-        if_ok!(write!(self.wr, ": "));
+        try!(write!(self.wr, ": "));
         f(self);
     }
 }

src/libextra/stats.rs

@@ -376,48 +376,48 @@ pub fn write_boxplot(w: &mut io::Writer, s: &Summary,
     let range_width = width_hint - overhead_width;;
     let char_step = range / (range_width as f64);
 
-    if_ok!(write!(w, "{} |", lostr));
+    try!(write!(w, "{} |", lostr));
 
     let mut c = 0;
     let mut v = lo;
 
     while c < range_width && v < s.min {
-        if_ok!(write!(w, " "));
+        try!(write!(w, " "));
         v += char_step;
         c += 1;
     }
-    if_ok!(write!(w, "["));
+    try!(write!(w, "["));
     c += 1;
     while c < range_width && v < q1 {
-        if_ok!(write!(w, "-"));
+        try!(write!(w, "-"));
         v += char_step;
         c += 1;
     }
     while c < range_width && v < q2 {
-        if_ok!(write!(w, "*"));
+        try!(write!(w, "*"));
         v += char_step;
         c += 1;
     }
-    if_ok!(write!(w, r"\#"));
+    try!(write!(w, r"\#"));
     c += 1;
     while c < range_width && v < q3 {
-        if_ok!(write!(w, "*"));
+        try!(write!(w, "*"));
         v += char_step;
         c += 1;
     }
     while c < range_width && v < s.max {
-        if_ok!(write!(w, "-"));
+        try!(write!(w, "-"));
         v += char_step;
         c += 1;
     }
-    if_ok!(write!(w, "]"));
+    try!(write!(w, "]"));
     while c < range_width {
-        if_ok!(write!(w, " "));
+        try!(write!(w, " "));
         v += char_step;
         c += 1;
     }
 
-    if_ok!(write!(w, "| {}", histr));
+    try!(write!(w, "| {}", histr));
     Ok(())
 }
 

src/libnative/io/pipe_unix.rs

@@ -77,8 +77,8 @@ impl Drop for Inner {
 }
 
 fn connect(addr: &CString, ty: libc::c_int) -> IoResult<Inner> {
-    let (addr, len) = if_ok!(addr_to_sockaddr_un(addr));
-    let inner = Inner { fd: if_ok!(unix_socket(ty)) };
+    let (addr, len) = try!(addr_to_sockaddr_un(addr));
+    let inner = Inner { fd: try!(unix_socket(ty)) };
     let addrp = &addr as *libc::sockaddr_storage;
     match retry(|| unsafe {
         libc::connect(inner.fd, addrp as *libc::sockaddr,
@@ -90,8 +90,8 @@ fn connect(addr: &CString, ty: libc::c_int) -> IoResult<Inner> {
 }
 
 fn bind(addr: &CString, ty: libc::c_int) -> IoResult<Inner> {
-    let (addr, len) = if_ok!(addr_to_sockaddr_un(addr));
-    let inner = Inner { fd: if_ok!(unix_socket(ty)) };
+    let (addr, len) = try!(addr_to_sockaddr_un(addr));
+    let inner = Inner { fd: try!(unix_socket(ty)) };
     let addrp = &addr as *libc::sockaddr_storage;
     match unsafe {
         libc::bind(inner.fd, addrp as *libc::sockaddr, len as libc::socklen_t)
@@ -198,7 +198,7 @@ impl UnixDatagram {
     }
 
     pub fn sendto(&mut self, buf: &[u8], dst: &CString) -> IoResult<()> {
-        let (dst, len) = if_ok!(addr_to_sockaddr_un(dst));
+        let (dst, len) = try!(addr_to_sockaddr_un(dst));
         let dstp = &dst as *libc::sockaddr_storage;
         let ret = retry(|| unsafe {
             libc::sendto(self.fd(),